From: Deepak Kumar Singh <[email protected]>
Some transports like Glink support the state notifications between
clients using flow control signals similar to serial protocol signals.
Local glink client drivers can send and receive flow control status
to glink clients running on remote processors.
Add APIs to support sending and receiving of flow control status by
rpmsg clients.
Signed-off-by: Deepak Kumar Singh <[email protected]>
Signed-off-by: Sarannya S <[email protected]>
---
drivers/rpmsg/rpmsg_core.c | 21 +++++++++++++++++++++
drivers/rpmsg/rpmsg_internal.h | 2 ++
include/linux/rpmsg.h | 15 +++++++++++++++
3 files changed, 38 insertions(+)
diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
index a2207c0..e8bbe05 100644
--- a/drivers/rpmsg/rpmsg_core.c
+++ b/drivers/rpmsg/rpmsg_core.c
@@ -331,6 +331,25 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
EXPORT_SYMBOL(rpmsg_trysend_offchannel);
/**
+ * rpmsg_set_flow_control() - sets/clears serial flow control signals
+ * @ept: the rpmsg endpoint
+ * @enable: pause/resume incoming data flow
+ * @dst: destination address of the endpoint
+ *
+ * Return: 0 on success and an appropriate error value on failure.
+ */
+int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst)
+{
+ if (WARN_ON(!ept))
+ return -EINVAL;
+ if (!ept->ops->set_flow_control)
+ return -ENXIO;
+
+ return ept->ops->set_flow_control(ept, enable, dst);
+}
+EXPORT_SYMBOL_GPL(rpmsg_set_flow_control);
+
+/**
* rpmsg_get_mtu() - get maximum transmission buffer size for sending message.
* @ept: the rpmsg endpoint
*
@@ -539,6 +558,8 @@ static int rpmsg_dev_probe(struct device *dev)
rpdev->ept = ept;
rpdev->src = ept->addr;
+
+ ept->flow_cb = rpdrv->flowcontrol;
}
err = rpdrv->probe(rpdev);
diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h
index 39b646d..b6efd3e 100644
--- a/drivers/rpmsg/rpmsg_internal.h
+++ b/drivers/rpmsg/rpmsg_internal.h
@@ -55,6 +55,7 @@ struct rpmsg_device_ops {
* @trysendto: see @rpmsg_trysendto(), optional
* @trysend_offchannel: see @rpmsg_trysend_offchannel(), optional
* @poll: see @rpmsg_poll(), optional
+ * @set_flow_control: see @rpmsg_set_flow_control(), optional
* @get_mtu: see @rpmsg_get_mtu(), optional
*
* Indirection table for the operations that a rpmsg backend should implement.
@@ -75,6 +76,7 @@ struct rpmsg_endpoint_ops {
void *data, int len);
__poll_t (*poll)(struct rpmsg_endpoint *ept, struct file *filp,
poll_table *wait);
+ int (*set_flow_control)(struct rpmsg_endpoint *ept, bool enable, u32 dst);
ssize_t (*get_mtu)(struct rpmsg_endpoint *ept);
};
diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
index 523c98b..a0e9d38 100644
--- a/include/linux/rpmsg.h
+++ b/include/linux/rpmsg.h
@@ -64,12 +64,14 @@ struct rpmsg_device {
};
typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32);
+typedef int (*rpmsg_flowcontrol_cb_t)(struct rpmsg_device *, void *, bool);
/**
* struct rpmsg_endpoint - binds a local rpmsg address to its user
* @rpdev: rpmsg channel device
* @refcount: when this drops to zero, the ept is deallocated
* @cb: rx callback handler
+ * @flow_cb: remote flow control callback handler
* @cb_lock: must be taken before accessing/changing @cb
* @addr: local rpmsg address
* @priv: private data for the driver's use
@@ -92,6 +94,7 @@ struct rpmsg_endpoint {
struct rpmsg_device *rpdev;
struct kref refcount;
rpmsg_rx_cb_t cb;
+ rpmsg_flowcontrol_cb_t flow_cb;
struct mutex cb_lock;
u32 addr;
void *priv;
@@ -106,6 +109,7 @@ struct rpmsg_endpoint {
* @probe: invoked when a matching rpmsg channel (i.e. device) is found
* @remove: invoked when the rpmsg channel is removed
* @callback: invoked when an inbound message is received on the channel
+ * @flowcontrol: invoked when remote side flow control status is received
*/
struct rpmsg_driver {
struct device_driver drv;
@@ -113,6 +117,7 @@ struct rpmsg_driver {
int (*probe)(struct rpmsg_device *dev);
void (*remove)(struct rpmsg_device *dev);
int (*callback)(struct rpmsg_device *, void *, int, void *, u32);
+ int (*flowcontrol)(struct rpmsg_device *, void *, bool);
};
static inline u16 rpmsg16_to_cpu(struct rpmsg_device *rpdev, __rpmsg16 val)
@@ -192,6 +197,8 @@ __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept);
+int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst);
+
#else
static inline int rpmsg_register_device_override(struct rpmsg_device *rpdev,
@@ -316,6 +323,14 @@ static inline ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept)
return -ENXIO;
}
+static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst)
+{
+ /* This shouldn't be possible */
+ WARN_ON(1);
+
+ return -ENXIO;
+}
+
#endif /* IS_ENABLED(CONFIG_RPMSG) */
/* use a macro to avoid include chaining to get THIS_MODULE */
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
Hello,
On 4/22/23 12:42, Sarannya S wrote:
> From: Deepak Kumar Singh <[email protected]>
>
> Some transports like Glink support the state notifications between
> clients using flow control signals similar to serial protocol signals.
> Local glink client drivers can send and receive flow control status
> to glink clients running on remote processors.
>
> Add APIs to support sending and receiving of flow control status by
> rpmsg clients.
>
> Signed-off-by: Deepak Kumar Singh <[email protected]>
> Signed-off-by: Sarannya S <[email protected]>
> ---
> drivers/rpmsg/rpmsg_core.c | 21 +++++++++++++++++++++
> drivers/rpmsg/rpmsg_internal.h | 2 ++
> include/linux/rpmsg.h | 15 +++++++++++++++
> 3 files changed, 38 insertions(+)
>
> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> index a2207c0..e8bbe05 100644
> --- a/drivers/rpmsg/rpmsg_core.c
> +++ b/drivers/rpmsg/rpmsg_core.c
> @@ -331,6 +331,25 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
> EXPORT_SYMBOL(rpmsg_trysend_offchannel);
>
> /**
> + * rpmsg_set_flow_control() - sets/clears serial flow control signals
> + * @ept: the rpmsg endpoint
> + * @enable: pause/resume incoming data flow
> + * @dst: destination address of the endpoint
> + *
> + * Return: 0 on success and an appropriate error value on failure.
> + */
> +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst)
> +{
> + if (WARN_ON(!ept))
> + return -EINVAL;
> + if (!ept->ops->set_flow_control)
> + return -ENXIO;
Here we return an error if the backend does not implement the ops.
But the set_flow_control ops is optional.
Should we return 0 instead with a debug message?
> +
> + return ept->ops->set_flow_control(ept, enable, dst);
> +}
> +EXPORT_SYMBOL_GPL(rpmsg_set_flow_control);
> +
> +/**
> * rpmsg_get_mtu() - get maximum transmission buffer size for sending message.
> * @ept: the rpmsg endpoint
> *
> @@ -539,6 +558,8 @@ static int rpmsg_dev_probe(struct device *dev)
>
> rpdev->ept = ept;
> rpdev->src = ept->addr;
> +
> + ept->flow_cb = rpdrv->flowcontrol;
> }
>
> err = rpdrv->probe(rpdev);
> diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h
> index 39b646d..b6efd3e 100644
> --- a/drivers/rpmsg/rpmsg_internal.h
> +++ b/drivers/rpmsg/rpmsg_internal.h
> @@ -55,6 +55,7 @@ struct rpmsg_device_ops {
> * @trysendto: see @rpmsg_trysendto(), optional
> * @trysend_offchannel: see @rpmsg_trysend_offchannel(), optional
> * @poll: see @rpmsg_poll(), optional
> + * @set_flow_control: see @rpmsg_set_flow_control(), optional
> * @get_mtu: see @rpmsg_get_mtu(), optional
> *
> * Indirection table for the operations that a rpmsg backend should implement.
> @@ -75,6 +76,7 @@ struct rpmsg_endpoint_ops {
> void *data, int len);
> __poll_t (*poll)(struct rpmsg_endpoint *ept, struct file *filp,
> poll_table *wait);
> + int (*set_flow_control)(struct rpmsg_endpoint *ept, bool enable, u32 dst);
> ssize_t (*get_mtu)(struct rpmsg_endpoint *ept);
> };
>
> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
> index 523c98b..a0e9d38 100644
> --- a/include/linux/rpmsg.h
> +++ b/include/linux/rpmsg.h
> @@ -64,12 +64,14 @@ struct rpmsg_device {
> };
>
> typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32);
> +typedef int (*rpmsg_flowcontrol_cb_t)(struct rpmsg_device *, void *, bool);
>
> /**
> * struct rpmsg_endpoint - binds a local rpmsg address to its user
> * @rpdev: rpmsg channel device
> * @refcount: when this drops to zero, the ept is deallocated
> * @cb: rx callback handler
> + * @flow_cb: remote flow control callback handler
> * @cb_lock: must be taken before accessing/changing @cb
> * @addr: local rpmsg address
> * @priv: private data for the driver's use
> @@ -92,6 +94,7 @@ struct rpmsg_endpoint {
> struct rpmsg_device *rpdev;
> struct kref refcount;
> rpmsg_rx_cb_t cb;
> + rpmsg_flowcontrol_cb_t flow_cb;
> struct mutex cb_lock;
> u32 addr;
> void *priv;
> @@ -106,6 +109,7 @@ struct rpmsg_endpoint {
> * @probe: invoked when a matching rpmsg channel (i.e. device) is found
> * @remove: invoked when the rpmsg channel is removed
> * @callback: invoked when an inbound message is received on the channel
> + * @flowcontrol: invoked when remote side flow control status is received
> */
> struct rpmsg_driver {
> struct device_driver drv;
> @@ -113,6 +117,7 @@ struct rpmsg_driver {
> int (*probe)(struct rpmsg_device *dev);
> void (*remove)(struct rpmsg_device *dev);
> int (*callback)(struct rpmsg_device *, void *, int, void *, u32);
> + int (*flowcontrol)(struct rpmsg_device *, void *, bool);
I wonder here if we should also add a parameter for the remote source address.
This parameter is already exist for the
int (*callback)(struct rpmsg_device *, void *, int, void *, u32)
useful in case of point to multi point communication...
Regards,
Arnaud
> };
>
> static inline u16 rpmsg16_to_cpu(struct rpmsg_device *rpdev, __rpmsg16 val)
> @@ -192,6 +197,8 @@ __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
>
> ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept);
>
> +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst);
> +
> #else
>
> static inline int rpmsg_register_device_override(struct rpmsg_device *rpdev,
> @@ -316,6 +323,14 @@ static inline ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept)
> return -ENXIO;
> }
>
> +static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst)
> +{
> + /* This shouldn't be possible */
> + WARN_ON(1);
> +
> + return -ENXIO;
> +}
> +
> #endif /* IS_ENABLED(CONFIG_RPMSG) */
>
> /* use a macro to avoid include chaining to get THIS_MODULE */
On Mon, Apr 24, 2023 at 02:49:29PM +0200, Arnaud POULIQUEN wrote:
> Hello,
>
> On 4/22/23 12:42, Sarannya S wrote:
> > From: Deepak Kumar Singh <[email protected]>
> >
> > Some transports like Glink support the state notifications between
> > clients using flow control signals similar to serial protocol signals.
> > Local glink client drivers can send and receive flow control status
> > to glink clients running on remote processors.
> >
> > Add APIs to support sending and receiving of flow control status by
> > rpmsg clients.
> >
> > Signed-off-by: Deepak Kumar Singh <[email protected]>
> > Signed-off-by: Sarannya S <[email protected]>
> > ---
> > drivers/rpmsg/rpmsg_core.c | 21 +++++++++++++++++++++
> > drivers/rpmsg/rpmsg_internal.h | 2 ++
> > include/linux/rpmsg.h | 15 +++++++++++++++
> > 3 files changed, 38 insertions(+)
> >
> > diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> > index a2207c0..e8bbe05 100644
> > --- a/drivers/rpmsg/rpmsg_core.c
> > +++ b/drivers/rpmsg/rpmsg_core.c
> > @@ -331,6 +331,25 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
> > EXPORT_SYMBOL(rpmsg_trysend_offchannel);
> >
> > /**
> > + * rpmsg_set_flow_control() - sets/clears serial flow control signals
> > + * @ept: the rpmsg endpoint
> > + * @enable: pause/resume incoming data flow
> > + * @dst: destination address of the endpoint
> > + *
> > + * Return: 0 on success and an appropriate error value on failure.
> > + */
> > +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst)
> > +{
> > + if (WARN_ON(!ept))
> > + return -EINVAL;
> > + if (!ept->ops->set_flow_control)
> > + return -ENXIO;
>
> Here we return an error if the backend does not implement the ops.
> But the set_flow_control ops is optional.
> Should we return 0 instead with a debug message?
>
It seems reasonable to allow the software to react to the absence of
flow control support, so a debug message wouldn't help.
But advertising that more explicitly by returning something like
EOPNOTSUPP seems better.
Regards,
Bjorn
On Sat, Apr 22, 2023 at 04:12:05PM +0530, Sarannya S wrote:
> From: Deepak Kumar Singh <[email protected]>
>
> Some transports like Glink support the state notifications between
> clients using flow control signals similar to serial protocol signals.
> Local glink client drivers can send and receive flow control status
> to glink clients running on remote processors.
>
> Add APIs to support sending and receiving of flow control status by
> rpmsg clients.
>
> Signed-off-by: Deepak Kumar Singh <[email protected]>
> Signed-off-by: Sarannya S <[email protected]>
> ---
> drivers/rpmsg/rpmsg_core.c | 21 +++++++++++++++++++++
> drivers/rpmsg/rpmsg_internal.h | 2 ++
> include/linux/rpmsg.h | 15 +++++++++++++++
> 3 files changed, 38 insertions(+)
>
> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> index a2207c0..e8bbe05 100644
> --- a/drivers/rpmsg/rpmsg_core.c
> +++ b/drivers/rpmsg/rpmsg_core.c
> @@ -331,6 +331,25 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
> EXPORT_SYMBOL(rpmsg_trysend_offchannel);
>
> /**
> + * rpmsg_set_flow_control() - sets/clears serial flow control signals
> + * @ept: the rpmsg endpoint
> + * @enable: pause/resume incoming data flow
As shown in the discussion, it's still not clear what true/false means.
Also, let's try to clarify that it's a request for the other side to do
something:
* rpmsg_set_flow_control() - request remote to pause/resume transmission
* ...
* @enable: flow restricted
* ...
PS. There's a stray space at the end of the line.
> + * @dst: destination address of the endpoint
> + *
> + * Return: 0 on success and an appropriate error value on failure.
> + */
> +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst)
> +{
> + if (WARN_ON(!ept))
> + return -EINVAL;
> + if (!ept->ops->set_flow_control)
> + return -ENXIO;
> +
> + return ept->ops->set_flow_control(ept, enable, dst);
> +}
> +EXPORT_SYMBOL_GPL(rpmsg_set_flow_control);
> +
> +/**
> * rpmsg_get_mtu() - get maximum transmission buffer size for sending message.
> * @ept: the rpmsg endpoint
> *
> @@ -539,6 +558,8 @@ static int rpmsg_dev_probe(struct device *dev)
>
> rpdev->ept = ept;
> rpdev->src = ept->addr;
> +
> + ept->flow_cb = rpdrv->flowcontrol;
> }
>
> err = rpdrv->probe(rpdev);
> diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h
> index 39b646d..b6efd3e 100644
> --- a/drivers/rpmsg/rpmsg_internal.h
> +++ b/drivers/rpmsg/rpmsg_internal.h
> @@ -55,6 +55,7 @@ struct rpmsg_device_ops {
> * @trysendto: see @rpmsg_trysendto(), optional
> * @trysend_offchannel: see @rpmsg_trysend_offchannel(), optional
> * @poll: see @rpmsg_poll(), optional
> + * @set_flow_control: see @rpmsg_set_flow_control(), optional
> * @get_mtu: see @rpmsg_get_mtu(), optional
> *
> * Indirection table for the operations that a rpmsg backend should implement.
> @@ -75,6 +76,7 @@ struct rpmsg_endpoint_ops {
> void *data, int len);
> __poll_t (*poll)(struct rpmsg_endpoint *ept, struct file *filp,
> poll_table *wait);
> + int (*set_flow_control)(struct rpmsg_endpoint *ept, bool enable, u32 dst);
> ssize_t (*get_mtu)(struct rpmsg_endpoint *ept);
> };
>
> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
> index 523c98b..a0e9d38 100644
> --- a/include/linux/rpmsg.h
> +++ b/include/linux/rpmsg.h
> @@ -64,12 +64,14 @@ struct rpmsg_device {
> };
>
> typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32);
> +typedef int (*rpmsg_flowcontrol_cb_t)(struct rpmsg_device *, void *, bool);
>
> /**
> * struct rpmsg_endpoint - binds a local rpmsg address to its user
> * @rpdev: rpmsg channel device
> * @refcount: when this drops to zero, the ept is deallocated
> * @cb: rx callback handler
> + * @flow_cb: remote flow control callback handler
> * @cb_lock: must be taken before accessing/changing @cb
> * @addr: local rpmsg address
> * @priv: private data for the driver's use
> @@ -92,6 +94,7 @@ struct rpmsg_endpoint {
> struct rpmsg_device *rpdev;
> struct kref refcount;
> rpmsg_rx_cb_t cb;
> + rpmsg_flowcontrol_cb_t flow_cb;
> struct mutex cb_lock;
> u32 addr;
> void *priv;
> @@ -106,6 +109,7 @@ struct rpmsg_endpoint {
> * @probe: invoked when a matching rpmsg channel (i.e. device) is found
> * @remove: invoked when the rpmsg channel is removed
> * @callback: invoked when an inbound message is received on the channel
> + * @flowcontrol: invoked when remote side flow control status is received
s/status/request/
Regards,
Bjorn
> */
> struct rpmsg_driver {
> struct device_driver drv;
> @@ -113,6 +117,7 @@ struct rpmsg_driver {
> int (*probe)(struct rpmsg_device *dev);
> void (*remove)(struct rpmsg_device *dev);
> int (*callback)(struct rpmsg_device *, void *, int, void *, u32);
> + int (*flowcontrol)(struct rpmsg_device *, void *, bool);
> };
>
> static inline u16 rpmsg16_to_cpu(struct rpmsg_device *rpdev, __rpmsg16 val)
> @@ -192,6 +197,8 @@ __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
>
> ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept);
>
> +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst);
> +
> #else
>
> static inline int rpmsg_register_device_override(struct rpmsg_device *rpdev,
> @@ -316,6 +323,14 @@ static inline ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept)
> return -ENXIO;
> }
>
> +static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst)
> +{
> + /* This shouldn't be possible */
> + WARN_ON(1);
> +
> + return -ENXIO;
> +}
> +
> #endif /* IS_ENABLED(CONFIG_RPMSG) */
>
> /* use a macro to avoid include chaining to get THIS_MODULE */
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
Hi,
On 6/14/23 17:24, Bjorn Andersson wrote:
> On Mon, Apr 24, 2023 at 02:49:29PM +0200, Arnaud POULIQUEN wrote:
>> Hello,
>>
>> On 4/22/23 12:42, Sarannya S wrote:
>>> From: Deepak Kumar Singh <[email protected]>
>>>
>>> Some transports like Glink support the state notifications between
>>> clients using flow control signals similar to serial protocol signals.
>>> Local glink client drivers can send and receive flow control status
>>> to glink clients running on remote processors.
>>>
>>> Add APIs to support sending and receiving of flow control status by
>>> rpmsg clients.
>>>
>>> Signed-off-by: Deepak Kumar Singh <[email protected]>
>>> Signed-off-by: Sarannya S <[email protected]>
>>> ---
>>> drivers/rpmsg/rpmsg_core.c | 21 +++++++++++++++++++++
>>> drivers/rpmsg/rpmsg_internal.h | 2 ++
>>> include/linux/rpmsg.h | 15 +++++++++++++++
>>> 3 files changed, 38 insertions(+)
>>>
>>> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
>>> index a2207c0..e8bbe05 100644
>>> --- a/drivers/rpmsg/rpmsg_core.c
>>> +++ b/drivers/rpmsg/rpmsg_core.c
>>> @@ -331,6 +331,25 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
>>> EXPORT_SYMBOL(rpmsg_trysend_offchannel);
>>>
>>> /**
>>> + * rpmsg_set_flow_control() - sets/clears serial flow control signals
>>> + * @ept: the rpmsg endpoint
>>> + * @enable: pause/resume incoming data flow
>>> + * @dst: destination address of the endpoint
>>> + *
>>> + * Return: 0 on success and an appropriate error value on failure.
>>> + */
>>> +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst)
>>> +{
>>> + if (WARN_ON(!ept))
>>> + return -EINVAL;
>>> + if (!ept->ops->set_flow_control)
>>> + return -ENXIO;
>>
>> Here we return an error if the backend does not implement the ops.
>> But the set_flow_control ops is optional.
>> Should we return 0 instead with a debug message?
>>
>
> It seems reasonable to allow the software to react to the absence of
> flow control support, so a debug message wouldn't help.
>
> But advertising that more explicitly by returning something like
> EOPNOTSUPP seems better.
Right, this seems more reliable.
Thanks,
Arnaud
>
> Regards,
> Bjorn
On 6/14/23 17:54, Bjorn Andersson wrote:
> On Sat, Apr 22, 2023 at 04:12:05PM +0530, Sarannya S wrote:
>> From: Deepak Kumar Singh <[email protected]>
>>
>> Some transports like Glink support the state notifications between
>> clients using flow control signals similar to serial protocol signals.
>> Local glink client drivers can send and receive flow control status
>> to glink clients running on remote processors.
>>
>> Add APIs to support sending and receiving of flow control status by
>> rpmsg clients.
>>
>> Signed-off-by: Deepak Kumar Singh <[email protected]>
>> Signed-off-by: Sarannya S <[email protected]>
>> ---
>> drivers/rpmsg/rpmsg_core.c | 21 +++++++++++++++++++++
>> drivers/rpmsg/rpmsg_internal.h | 2 ++
>> include/linux/rpmsg.h | 15 +++++++++++++++
>> 3 files changed, 38 insertions(+)
>>
>> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
>> index a2207c0..e8bbe05 100644
>> --- a/drivers/rpmsg/rpmsg_core.c
>> +++ b/drivers/rpmsg/rpmsg_core.c
>> @@ -331,6 +331,25 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
>> EXPORT_SYMBOL(rpmsg_trysend_offchannel);
>>
>> /**
>> + * rpmsg_set_flow_control() - sets/clears serial flow control signals
>> + * @ept: the rpmsg endpoint
>> + * @enable: pause/resume incoming data flow
>
> As shown in the discussion, it's still not clear what true/false means.
> Also, let's try to clarify that it's a request for the other side to do
> something:
>
> * rpmsg_set_flow_control() - request remote to pause/resume transmission
> * ...
> * @enable: flow restricted
> * ...
>
>
> PS. There's a stray space at the end of the line.
The notion of flow restricted seems to me also ambiguous. It does
not specify if the stream is limited in term of bandwidth or stopped.
What about using XON/XOFF as specified in software flow control[1]
XOFF Pause transmission
XON Resume transmission
or simply pause/resume definitions
[1]https://en.wikipedia.org/wiki/Software_flow_control
Regards,
Arnaud
>
>> + * @dst: destination address of the endpoint
>> + *
>> + * Return: 0 on success and an appropriate error value on failure.
>> + */
>> +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst)
>> +{
>> + if (WARN_ON(!ept))
>> + return -EINVAL;
>> + if (!ept->ops->set_flow_control)
>> + return -ENXIO;
>> +
>> + return ept->ops->set_flow_control(ept, enable, dst);
>> +}
>> +EXPORT_SYMBOL_GPL(rpmsg_set_flow_control);
>> +
>> +/**
>> * rpmsg_get_mtu() - get maximum transmission buffer size for sending message.
>> * @ept: the rpmsg endpoint
>> *
>> @@ -539,6 +558,8 @@ static int rpmsg_dev_probe(struct device *dev)
>>
>> rpdev->ept = ept;
>> rpdev->src = ept->addr;
>> +
>> + ept->flow_cb = rpdrv->flowcontrol;
>> }
>>
>> err = rpdrv->probe(rpdev);
>> diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h
>> index 39b646d..b6efd3e 100644
>> --- a/drivers/rpmsg/rpmsg_internal.h
>> +++ b/drivers/rpmsg/rpmsg_internal.h
>> @@ -55,6 +55,7 @@ struct rpmsg_device_ops {
>> * @trysendto: see @rpmsg_trysendto(), optional
>> * @trysend_offchannel: see @rpmsg_trysend_offchannel(), optional
>> * @poll: see @rpmsg_poll(), optional
>> + * @set_flow_control: see @rpmsg_set_flow_control(), optional
>> * @get_mtu: see @rpmsg_get_mtu(), optional
>> *
>> * Indirection table for the operations that a rpmsg backend should implement.
>> @@ -75,6 +76,7 @@ struct rpmsg_endpoint_ops {
>> void *data, int len);
>> __poll_t (*poll)(struct rpmsg_endpoint *ept, struct file *filp,
>> poll_table *wait);
>> + int (*set_flow_control)(struct rpmsg_endpoint *ept, bool enable, u32 dst);
>> ssize_t (*get_mtu)(struct rpmsg_endpoint *ept);
>> };
>>
>> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
>> index 523c98b..a0e9d38 100644
>> --- a/include/linux/rpmsg.h
>> +++ b/include/linux/rpmsg.h
>> @@ -64,12 +64,14 @@ struct rpmsg_device {
>> };
>>
>> typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32);
>> +typedef int (*rpmsg_flowcontrol_cb_t)(struct rpmsg_device *, void *, bool);
>>
>> /**
>> * struct rpmsg_endpoint - binds a local rpmsg address to its user
>> * @rpdev: rpmsg channel device
>> * @refcount: when this drops to zero, the ept is deallocated
>> * @cb: rx callback handler
>> + * @flow_cb: remote flow control callback handler
>> * @cb_lock: must be taken before accessing/changing @cb
>> * @addr: local rpmsg address
>> * @priv: private data for the driver's use
>> @@ -92,6 +94,7 @@ struct rpmsg_endpoint {
>> struct rpmsg_device *rpdev;
>> struct kref refcount;
>> rpmsg_rx_cb_t cb;
>> + rpmsg_flowcontrol_cb_t flow_cb;
>> struct mutex cb_lock;
>> u32 addr;
>> void *priv;
>> @@ -106,6 +109,7 @@ struct rpmsg_endpoint {
>> * @probe: invoked when a matching rpmsg channel (i.e. device) is found
>> * @remove: invoked when the rpmsg channel is removed
>> * @callback: invoked when an inbound message is received on the channel
>> + * @flowcontrol: invoked when remote side flow control status is received
>
> s/status/request/
>
> Regards,
> Bjorn
>
>> */
>> struct rpmsg_driver {
>> struct device_driver drv;
>> @@ -113,6 +117,7 @@ struct rpmsg_driver {
>> int (*probe)(struct rpmsg_device *dev);
>> void (*remove)(struct rpmsg_device *dev);
>> int (*callback)(struct rpmsg_device *, void *, int, void *, u32);
>> + int (*flowcontrol)(struct rpmsg_device *, void *, bool);
>> };
>>
>> static inline u16 rpmsg16_to_cpu(struct rpmsg_device *rpdev, __rpmsg16 val)
>> @@ -192,6 +197,8 @@ __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
>>
>> ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept);
>>
>> +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst);
>> +
>> #else
>>
>> static inline int rpmsg_register_device_override(struct rpmsg_device *rpdev,
>> @@ -316,6 +323,14 @@ static inline ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept)
>> return -ENXIO;
>> }
>>
>> +static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst)
>> +{
>> + /* This shouldn't be possible */
>> + WARN_ON(1);
>> +
>> + return -ENXIO;
>> +}
>> +
>> #endif /* IS_ENABLED(CONFIG_RPMSG) */
>>
>> /* use a macro to avoid include chaining to get THIS_MODULE */
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
>> a Linux Foundation Collaborative Project
>>
On Thu, Jun 15, 2023 at 11:01:14AM +0200, Arnaud POULIQUEN wrote:
>
>
> On 6/14/23 17:54, Bjorn Andersson wrote:
> > On Sat, Apr 22, 2023 at 04:12:05PM +0530, Sarannya S wrote:
> >> From: Deepak Kumar Singh <[email protected]>
> >>
> >> Some transports like Glink support the state notifications between
> >> clients using flow control signals similar to serial protocol signals.
> >> Local glink client drivers can send and receive flow control status
> >> to glink clients running on remote processors.
> >>
> >> Add APIs to support sending and receiving of flow control status by
> >> rpmsg clients.
> >>
> >> Signed-off-by: Deepak Kumar Singh <[email protected]>
> >> Signed-off-by: Sarannya S <[email protected]>
> >> ---
> >> drivers/rpmsg/rpmsg_core.c | 21 +++++++++++++++++++++
> >> drivers/rpmsg/rpmsg_internal.h | 2 ++
> >> include/linux/rpmsg.h | 15 +++++++++++++++
> >> 3 files changed, 38 insertions(+)
> >>
> >> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> >> index a2207c0..e8bbe05 100644
> >> --- a/drivers/rpmsg/rpmsg_core.c
> >> +++ b/drivers/rpmsg/rpmsg_core.c
> >> @@ -331,6 +331,25 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
> >> EXPORT_SYMBOL(rpmsg_trysend_offchannel);
> >>
> >> /**
> >> + * rpmsg_set_flow_control() - sets/clears serial flow control signals
> >> + * @ept: the rpmsg endpoint
> >> + * @enable: pause/resume incoming data flow
> >
> > As shown in the discussion, it's still not clear what true/false means.
> > Also, let's try to clarify that it's a request for the other side to do
> > something:
> >
> > * rpmsg_set_flow_control() - request remote to pause/resume transmission
> > * ...
> > * @enable: flow restricted
> > * ...
> >
> >
> > PS. There's a stray space at the end of the line.
>
> The notion of flow restricted seems to me also ambiguous. It does
> not specify if the stream is limited in term of bandwidth or stopped.
>
> What about using XON/XOFF as specified in software flow control[1]
>
> XOFF Pause transmission
> XON Resume transmission
>
> or simply pause/resume definitions
>
I agree, that's still ambiguous.
I was concerned about expressing it such that the reader would assume
that calling this means there will be no more data coming, but there
might be things in the queues etc. Expressing it in terms of the state
of transmission is clearer.
/*
* rpmsg_set_flow_control() - request remote to pause/resume transmission
...
* @enable: Pause transmission
...
*/
Does that sound okay and clear to you?
Thanks,
Bjorn
> [1]https://en.wikipedia.org/wiki/Software_flow_control
>
> Regards,
> Arnaud
>
> >
> >> + * @dst: destination address of the endpoint
> >> + *
> >> + * Return: 0 on success and an appropriate error value on failure.
> >> + */
> >> +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst)
> >> +{
> >> + if (WARN_ON(!ept))
> >> + return -EINVAL;
> >> + if (!ept->ops->set_flow_control)
> >> + return -ENXIO;
> >> +
> >> + return ept->ops->set_flow_control(ept, enable, dst);
> >> +}
> >> +EXPORT_SYMBOL_GPL(rpmsg_set_flow_control);
> >> +
> >> +/**
> >> * rpmsg_get_mtu() - get maximum transmission buffer size for sending message.
> >> * @ept: the rpmsg endpoint
> >> *
> >> @@ -539,6 +558,8 @@ static int rpmsg_dev_probe(struct device *dev)
> >>
> >> rpdev->ept = ept;
> >> rpdev->src = ept->addr;
> >> +
> >> + ept->flow_cb = rpdrv->flowcontrol;
> >> }
> >>
> >> err = rpdrv->probe(rpdev);
> >> diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h
> >> index 39b646d..b6efd3e 100644
> >> --- a/drivers/rpmsg/rpmsg_internal.h
> >> +++ b/drivers/rpmsg/rpmsg_internal.h
> >> @@ -55,6 +55,7 @@ struct rpmsg_device_ops {
> >> * @trysendto: see @rpmsg_trysendto(), optional
> >> * @trysend_offchannel: see @rpmsg_trysend_offchannel(), optional
> >> * @poll: see @rpmsg_poll(), optional
> >> + * @set_flow_control: see @rpmsg_set_flow_control(), optional
> >> * @get_mtu: see @rpmsg_get_mtu(), optional
> >> *
> >> * Indirection table for the operations that a rpmsg backend should implement.
> >> @@ -75,6 +76,7 @@ struct rpmsg_endpoint_ops {
> >> void *data, int len);
> >> __poll_t (*poll)(struct rpmsg_endpoint *ept, struct file *filp,
> >> poll_table *wait);
> >> + int (*set_flow_control)(struct rpmsg_endpoint *ept, bool enable, u32 dst);
> >> ssize_t (*get_mtu)(struct rpmsg_endpoint *ept);
> >> };
> >>
> >> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
> >> index 523c98b..a0e9d38 100644
> >> --- a/include/linux/rpmsg.h
> >> +++ b/include/linux/rpmsg.h
> >> @@ -64,12 +64,14 @@ struct rpmsg_device {
> >> };
> >>
> >> typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32);
> >> +typedef int (*rpmsg_flowcontrol_cb_t)(struct rpmsg_device *, void *, bool);
> >>
> >> /**
> >> * struct rpmsg_endpoint - binds a local rpmsg address to its user
> >> * @rpdev: rpmsg channel device
> >> * @refcount: when this drops to zero, the ept is deallocated
> >> * @cb: rx callback handler
> >> + * @flow_cb: remote flow control callback handler
> >> * @cb_lock: must be taken before accessing/changing @cb
> >> * @addr: local rpmsg address
> >> * @priv: private data for the driver's use
> >> @@ -92,6 +94,7 @@ struct rpmsg_endpoint {
> >> struct rpmsg_device *rpdev;
> >> struct kref refcount;
> >> rpmsg_rx_cb_t cb;
> >> + rpmsg_flowcontrol_cb_t flow_cb;
> >> struct mutex cb_lock;
> >> u32 addr;
> >> void *priv;
> >> @@ -106,6 +109,7 @@ struct rpmsg_endpoint {
> >> * @probe: invoked when a matching rpmsg channel (i.e. device) is found
> >> * @remove: invoked when the rpmsg channel is removed
> >> * @callback: invoked when an inbound message is received on the channel
> >> + * @flowcontrol: invoked when remote side flow control status is received
> >
> > s/status/request/
> >
> > Regards,
> > Bjorn
> >
> >> */
> >> struct rpmsg_driver {
> >> struct device_driver drv;
> >> @@ -113,6 +117,7 @@ struct rpmsg_driver {
> >> int (*probe)(struct rpmsg_device *dev);
> >> void (*remove)(struct rpmsg_device *dev);
> >> int (*callback)(struct rpmsg_device *, void *, int, void *, u32);
> >> + int (*flowcontrol)(struct rpmsg_device *, void *, bool);
> >> };
> >>
> >> static inline u16 rpmsg16_to_cpu(struct rpmsg_device *rpdev, __rpmsg16 val)
> >> @@ -192,6 +197,8 @@ __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
> >>
> >> ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept);
> >>
> >> +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst);
> >> +
> >> #else
> >>
> >> static inline int rpmsg_register_device_override(struct rpmsg_device *rpdev,
> >> @@ -316,6 +323,14 @@ static inline ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept)
> >> return -ENXIO;
> >> }
> >>
> >> +static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst)
> >> +{
> >> + /* This shouldn't be possible */
> >> + WARN_ON(1);
> >> +
> >> + return -ENXIO;
> >> +}
> >> +
> >> #endif /* IS_ENABLED(CONFIG_RPMSG) */
> >>
> >> /* use a macro to avoid include chaining to get THIS_MODULE */
> >> --
> >> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> >> a Linux Foundation Collaborative Project
> >>
On 6/15/23 16:50, Bjorn Andersson wrote:
> On Thu, Jun 15, 2023 at 11:01:14AM +0200, Arnaud POULIQUEN wrote:
>>
>>
>> On 6/14/23 17:54, Bjorn Andersson wrote:
>>> On Sat, Apr 22, 2023 at 04:12:05PM +0530, Sarannya S wrote:
>>>> From: Deepak Kumar Singh <[email protected]>
>>>>
>>>> Some transports like Glink support the state notifications between
>>>> clients using flow control signals similar to serial protocol signals.
>>>> Local glink client drivers can send and receive flow control status
>>>> to glink clients running on remote processors.
>>>>
>>>> Add APIs to support sending and receiving of flow control status by
>>>> rpmsg clients.
>>>>
>>>> Signed-off-by: Deepak Kumar Singh <[email protected]>
>>>> Signed-off-by: Sarannya S <[email protected]>
>>>> ---
>>>> drivers/rpmsg/rpmsg_core.c | 21 +++++++++++++++++++++
>>>> drivers/rpmsg/rpmsg_internal.h | 2 ++
>>>> include/linux/rpmsg.h | 15 +++++++++++++++
>>>> 3 files changed, 38 insertions(+)
>>>>
>>>> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
>>>> index a2207c0..e8bbe05 100644
>>>> --- a/drivers/rpmsg/rpmsg_core.c
>>>> +++ b/drivers/rpmsg/rpmsg_core.c
>>>> @@ -331,6 +331,25 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
>>>> EXPORT_SYMBOL(rpmsg_trysend_offchannel);
>>>>
>>>> /**
>>>> + * rpmsg_set_flow_control() - sets/clears serial flow control signals
>>>> + * @ept: the rpmsg endpoint
>>>> + * @enable: pause/resume incoming data flow
>>>
>>> As shown in the discussion, it's still not clear what true/false means.
>>> Also, let's try to clarify that it's a request for the other side to do
>>> something:
>>>
>>> * rpmsg_set_flow_control() - request remote to pause/resume transmission
>>> * ...
>>> * @enable: flow restricted
>>> * ...
>>>
>>>
>>> PS. There's a stray space at the end of the line.
>>
>> The notion of flow restricted seems to me also ambiguous. It does
>> not specify if the stream is limited in term of bandwidth or stopped.
>>
>> What about using XON/XOFF as specified in software flow control[1]
>>
>> XOFF Pause transmission
>> XON Resume transmission
>>
>> or simply pause/resume definitions
>>
>
> I agree, that's still ambiguous.
>
> I was concerned about expressing it such that the reader would assume
> that calling this means there will be no more data coming, but there
> might be things in the queues etc. Expressing it in terms of the state
> of transmission is clearer.
>
>
> /*
> * rpmsg_set_flow_control() - request remote to pause/resume transmission
> ...
> * @enable: Pause transmission
> ...
> */
>
> Does that sound okay and clear to you?
Much better! I still have a nitpicking point :)
What about replacing @enable variable by @pause to align the variable with the
usage?
/*
* rpmsg_set_flow_control() - request remote to pause/resume transmission
...
* @pause: set to 1 to pause transmission, to 0 to resume the transmission
...
*/
Thanks,
Arnaud
>
> Thanks,
> Bjorn
>
>> [1]https://en.wikipedia.org/wiki/Software_flow_control
>>
>> Regards,
>> Arnaud
>>
>>>
>>>> + * @dst: destination address of the endpoint
>>>> + *
>>>> + * Return: 0 on success and an appropriate error value on failure.
>>>> + */
>>>> +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst)
>>>> +{
>>>> + if (WARN_ON(!ept))
>>>> + return -EINVAL;
>>>> + if (!ept->ops->set_flow_control)
>>>> + return -ENXIO;
>>>> +
>>>> + return ept->ops->set_flow_control(ept, enable, dst);
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(rpmsg_set_flow_control);
>>>> +
>>>> +/**
>>>> * rpmsg_get_mtu() - get maximum transmission buffer size for sending message.
>>>> * @ept: the rpmsg endpoint
>>>> *
>>>> @@ -539,6 +558,8 @@ static int rpmsg_dev_probe(struct device *dev)
>>>>
>>>> rpdev->ept = ept;
>>>> rpdev->src = ept->addr;
>>>> +
>>>> + ept->flow_cb = rpdrv->flowcontrol;
>>>> }
>>>>
>>>> err = rpdrv->probe(rpdev);
>>>> diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h
>>>> index 39b646d..b6efd3e 100644
>>>> --- a/drivers/rpmsg/rpmsg_internal.h
>>>> +++ b/drivers/rpmsg/rpmsg_internal.h
>>>> @@ -55,6 +55,7 @@ struct rpmsg_device_ops {
>>>> * @trysendto: see @rpmsg_trysendto(), optional
>>>> * @trysend_offchannel: see @rpmsg_trysend_offchannel(), optional
>>>> * @poll: see @rpmsg_poll(), optional
>>>> + * @set_flow_control: see @rpmsg_set_flow_control(), optional
>>>> * @get_mtu: see @rpmsg_get_mtu(), optional
>>>> *
>>>> * Indirection table for the operations that a rpmsg backend should implement.
>>>> @@ -75,6 +76,7 @@ struct rpmsg_endpoint_ops {
>>>> void *data, int len);
>>>> __poll_t (*poll)(struct rpmsg_endpoint *ept, struct file *filp,
>>>> poll_table *wait);
>>>> + int (*set_flow_control)(struct rpmsg_endpoint *ept, bool enable, u32 dst);
>>>> ssize_t (*get_mtu)(struct rpmsg_endpoint *ept);
>>>> };
>>>>
>>>> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
>>>> index 523c98b..a0e9d38 100644
>>>> --- a/include/linux/rpmsg.h
>>>> +++ b/include/linux/rpmsg.h
>>>> @@ -64,12 +64,14 @@ struct rpmsg_device {
>>>> };
>>>>
>>>> typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32);
>>>> +typedef int (*rpmsg_flowcontrol_cb_t)(struct rpmsg_device *, void *, bool);
>>>>
>>>> /**
>>>> * struct rpmsg_endpoint - binds a local rpmsg address to its user
>>>> * @rpdev: rpmsg channel device
>>>> * @refcount: when this drops to zero, the ept is deallocated
>>>> * @cb: rx callback handler
>>>> + * @flow_cb: remote flow control callback handler
>>>> * @cb_lock: must be taken before accessing/changing @cb
>>>> * @addr: local rpmsg address
>>>> * @priv: private data for the driver's use
>>>> @@ -92,6 +94,7 @@ struct rpmsg_endpoint {
>>>> struct rpmsg_device *rpdev;
>>>> struct kref refcount;
>>>> rpmsg_rx_cb_t cb;
>>>> + rpmsg_flowcontrol_cb_t flow_cb;
>>>> struct mutex cb_lock;
>>>> u32 addr;
>>>> void *priv;
>>>> @@ -106,6 +109,7 @@ struct rpmsg_endpoint {
>>>> * @probe: invoked when a matching rpmsg channel (i.e. device) is found
>>>> * @remove: invoked when the rpmsg channel is removed
>>>> * @callback: invoked when an inbound message is received on the channel
>>>> + * @flowcontrol: invoked when remote side flow control status is received
>>>
>>> s/status/request/
>>>
>>> Regards,
>>> Bjorn
>>>
>>>> */
>>>> struct rpmsg_driver {
>>>> struct device_driver drv;
>>>> @@ -113,6 +117,7 @@ struct rpmsg_driver {
>>>> int (*probe)(struct rpmsg_device *dev);
>>>> void (*remove)(struct rpmsg_device *dev);
>>>> int (*callback)(struct rpmsg_device *, void *, int, void *, u32);
>>>> + int (*flowcontrol)(struct rpmsg_device *, void *, bool);
>>>> };
>>>>
>>>> static inline u16 rpmsg16_to_cpu(struct rpmsg_device *rpdev, __rpmsg16 val)
>>>> @@ -192,6 +197,8 @@ __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
>>>>
>>>> ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept);
>>>>
>>>> +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst);
>>>> +
>>>> #else
>>>>
>>>> static inline int rpmsg_register_device_override(struct rpmsg_device *rpdev,
>>>> @@ -316,6 +323,14 @@ static inline ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept)
>>>> return -ENXIO;
>>>> }
>>>>
>>>> +static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst)
>>>> +{
>>>> + /* This shouldn't be possible */
>>>> + WARN_ON(1);
>>>> +
>>>> + return -ENXIO;
>>>> +}
>>>> +
>>>> #endif /* IS_ENABLED(CONFIG_RPMSG) */
>>>>
>>>> /* use a macro to avoid include chaining to get THIS_MODULE */
>>>> --
>>>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
>>>> a Linux Foundation Collaborative Project
>>>>
On Thu, Jun 15, 2023 at 06:19:37PM +0200, Arnaud POULIQUEN wrote:
>
>
> On 6/15/23 16:50, Bjorn Andersson wrote:
> > On Thu, Jun 15, 2023 at 11:01:14AM +0200, Arnaud POULIQUEN wrote:
> >>
> >>
> >> On 6/14/23 17:54, Bjorn Andersson wrote:
> >>> On Sat, Apr 22, 2023 at 04:12:05PM +0530, Sarannya S wrote:
> >>>> From: Deepak Kumar Singh <[email protected]>
> >>>>
> >>>> Some transports like Glink support the state notifications between
> >>>> clients using flow control signals similar to serial protocol signals.
> >>>> Local glink client drivers can send and receive flow control status
> >>>> to glink clients running on remote processors.
> >>>>
> >>>> Add APIs to support sending and receiving of flow control status by
> >>>> rpmsg clients.
> >>>>
> >>>> Signed-off-by: Deepak Kumar Singh <[email protected]>
> >>>> Signed-off-by: Sarannya S <[email protected]>
> >>>> ---
> >>>> drivers/rpmsg/rpmsg_core.c | 21 +++++++++++++++++++++
> >>>> drivers/rpmsg/rpmsg_internal.h | 2 ++
> >>>> include/linux/rpmsg.h | 15 +++++++++++++++
> >>>> 3 files changed, 38 insertions(+)
> >>>>
> >>>> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> >>>> index a2207c0..e8bbe05 100644
> >>>> --- a/drivers/rpmsg/rpmsg_core.c
> >>>> +++ b/drivers/rpmsg/rpmsg_core.c
> >>>> @@ -331,6 +331,25 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
> >>>> EXPORT_SYMBOL(rpmsg_trysend_offchannel);
> >>>>
> >>>> /**
> >>>> + * rpmsg_set_flow_control() - sets/clears serial flow control signals
> >>>> + * @ept: the rpmsg endpoint
> >>>> + * @enable: pause/resume incoming data flow
> >>>
> >>> As shown in the discussion, it's still not clear what true/false means.
> >>> Also, let's try to clarify that it's a request for the other side to do
> >>> something:
> >>>
> >>> * rpmsg_set_flow_control() - request remote to pause/resume transmission
> >>> * ...
> >>> * @enable: flow restricted
> >>> * ...
> >>>
> >>>
> >>> PS. There's a stray space at the end of the line.
> >>
> >> The notion of flow restricted seems to me also ambiguous. It does
> >> not specify if the stream is limited in term of bandwidth or stopped.
> >>
> >> What about using XON/XOFF as specified in software flow control[1]
> >>
> >> XOFF Pause transmission
> >> XON Resume transmission
> >>
> >> or simply pause/resume definitions
> >>
> >
> > I agree, that's still ambiguous.
> >
> > I was concerned about expressing it such that the reader would assume
> > that calling this means there will be no more data coming, but there
> > might be things in the queues etc. Expressing it in terms of the state
> > of transmission is clearer.
> >
> >
> > /*
> > * rpmsg_set_flow_control() - request remote to pause/resume transmission
> > ...
> > * @enable: Pause transmission
> > ...
> > */
> >
> > Does that sound okay and clear to you?
>
> Much better! I still have a nitpicking point :)
> What about replacing @enable variable by @pause to align the variable with the
> usage?
> /*
> * rpmsg_set_flow_control() - request remote to pause/resume transmission
> ...
> * @pause: set to 1 to pause transmission, to 0 to resume the transmission
It's a boolean, so I think with your name change suggestion, together
with the function description, it should be clear enough what the two
states (true/false) means.
* @pause: Pause transmission
Thanks,
Bjorn
On 6/15/23 18:45, Bjorn Andersson wrote:
> On Thu, Jun 15, 2023 at 06:19:37PM +0200, Arnaud POULIQUEN wrote:
>>
>>
>> On 6/15/23 16:50, Bjorn Andersson wrote:
>>> On Thu, Jun 15, 2023 at 11:01:14AM +0200, Arnaud POULIQUEN wrote:
>>>>
>>>>
>>>> On 6/14/23 17:54, Bjorn Andersson wrote:
>>>>> On Sat, Apr 22, 2023 at 04:12:05PM +0530, Sarannya S wrote:
>>>>>> From: Deepak Kumar Singh <[email protected]>
>>>>>>
>>>>>> Some transports like Glink support the state notifications between
>>>>>> clients using flow control signals similar to serial protocol signals.
>>>>>> Local glink client drivers can send and receive flow control status
>>>>>> to glink clients running on remote processors.
>>>>>>
>>>>>> Add APIs to support sending and receiving of flow control status by
>>>>>> rpmsg clients.
>>>>>>
>>>>>> Signed-off-by: Deepak Kumar Singh <[email protected]>
>>>>>> Signed-off-by: Sarannya S <[email protected]>
>>>>>> ---
>>>>>> drivers/rpmsg/rpmsg_core.c | 21 +++++++++++++++++++++
>>>>>> drivers/rpmsg/rpmsg_internal.h | 2 ++
>>>>>> include/linux/rpmsg.h | 15 +++++++++++++++
>>>>>> 3 files changed, 38 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
>>>>>> index a2207c0..e8bbe05 100644
>>>>>> --- a/drivers/rpmsg/rpmsg_core.c
>>>>>> +++ b/drivers/rpmsg/rpmsg_core.c
>>>>>> @@ -331,6 +331,25 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
>>>>>> EXPORT_SYMBOL(rpmsg_trysend_offchannel);
>>>>>>
>>>>>> /**
>>>>>> + * rpmsg_set_flow_control() - sets/clears serial flow control signals
>>>>>> + * @ept: the rpmsg endpoint
>>>>>> + * @enable: pause/resume incoming data flow
>>>>>
>>>>> As shown in the discussion, it's still not clear what true/false means.
>>>>> Also, let's try to clarify that it's a request for the other side to do
>>>>> something:
>>>>>
>>>>> * rpmsg_set_flow_control() - request remote to pause/resume transmission
>>>>> * ...
>>>>> * @enable: flow restricted
>>>>> * ...
>>>>>
>>>>>
>>>>> PS. There's a stray space at the end of the line.
>>>>
>>>> The notion of flow restricted seems to me also ambiguous. It does
>>>> not specify if the stream is limited in term of bandwidth or stopped.
>>>>
>>>> What about using XON/XOFF as specified in software flow control[1]
>>>>
>>>> XOFF Pause transmission
>>>> XON Resume transmission
>>>>
>>>> or simply pause/resume definitions
>>>>
>>>
>>> I agree, that's still ambiguous.
>>>
>>> I was concerned about expressing it such that the reader would assume
>>> that calling this means there will be no more data coming, but there
>>> might be things in the queues etc. Expressing it in terms of the state
>>> of transmission is clearer.
>>>
>>>
>>> /*
>>> * rpmsg_set_flow_control() - request remote to pause/resume transmission
>>> ...
>>> * @enable: Pause transmission
>>> ...
>>> */
>>>
>>> Does that sound okay and clear to you?
>>
>> Much better! I still have a nitpicking point :)
>> What about replacing @enable variable by @pause to align the variable with the
>> usage?
>> /*
>> * rpmsg_set_flow_control() - request remote to pause/resume transmission
>> ...
>> * @pause: set to 1 to pause transmission, to 0 to resume the transmission
>
> It's a boolean, so I think with your name change suggestion, together
> with the function description, it should be clear enough what the two
> states (true/false) means.
>
> * @pause: Pause transmission
Ok for me
Thanks,
Arnaud
>
> Thanks,
> Bjorn