Added new IOCTLS- RPMSG_GET_OUTGOING_FLOWCONTROL and RPMSG_SET_INCOMING_FLOWCONTROL
to get/set the rpmsg char device's flow control signal.
Update the cmd name 'RPM_CMD_SIGNALS' to 'GLINK_CMD_SIGNALS'.
Changed 'remote_flow' to bool type, and updated it's evaluation.
Updated evaluation 'set' in rpmsg_char as 'set = !!arg'.
Addressed review comments to change variable names/descriptions.
Chris Lew (1):
rpmsg: glink: Add support to handle signals command
Deepak Kumar Singh (1):
rpmsg: core: Add signal API support
Sarannya S (1):
rpmsg: char: Add RPMSG GET/SET FLOWCONTROL IOCTL support
drivers/rpmsg/qcom_glink_native.c | 64 +++++++++++++++++++++++++++++++++++++++
drivers/rpmsg/rpmsg_char.c | 53 ++++++++++++++++++++++++++++----
drivers/rpmsg/rpmsg_core.c | 21 +++++++++++++
drivers/rpmsg/rpmsg_internal.h | 2 ++
include/linux/rpmsg.h | 15 +++++++++
include/uapi/linux/rpmsg.h | 11 ++++++-
6 files changed, 159 insertions(+), 7 deletions(-)
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
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..cd71a6a 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(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
From: Chris Lew <[email protected]>
Remote peripherals send signal notifications over glink with commandID 15.
Add support to send and receive the signal command and based signals
enable or disable flow control with remote host.
Signed-off-by: Chris Lew <[email protected]>
Signed-off-by: Deepak Kumar Singh <[email protected]>
Signed-off-by: Sarannya S <[email protected]>
---
drivers/rpmsg/qcom_glink_native.c | 64 +++++++++++++++++++++++++++++++++++++++
1 file changed, 64 insertions(+)
diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
index 01d2805..ff5e926 100644
--- a/drivers/rpmsg/qcom_glink_native.c
+++ b/drivers/rpmsg/qcom_glink_native.c
@@ -16,6 +16,7 @@
#include <linux/rpmsg.h>
#include <linux/sizes.h>
#include <linux/slab.h>
+#include <linux/termios.h>
#include <linux/workqueue.h>
#include <linux/mailbox_client.h>
@@ -197,9 +198,15 @@ static const struct rpmsg_endpoint_ops glink_endpoint_ops;
#define GLINK_CMD_TX_DATA_CONT 12
#define GLINK_CMD_READ_NOTIF 13
#define GLINK_CMD_RX_DONE_W_REUSE 14
+#define GLINK_CMD_SIGNALS 15
#define GLINK_FEATURE_INTENTLESS BIT(1)
+#define NATIVE_DTR_SIG NATIVE_DSR_SIG
+#define NATIVE_DSR_SIG BIT(31)
+#define NATIVE_RTS_SIG NATIVE_CTS_SIG
+#define NATIVE_CTS_SIG BIT(30)
+
static void qcom_glink_rx_done_work(struct work_struct *work);
static struct glink_channel *qcom_glink_alloc_channel(struct qcom_glink *glink,
@@ -1014,6 +1021,58 @@ static int qcom_glink_rx_open_ack(struct qcom_glink *glink, unsigned int lcid)
return 0;
}
+/**
+ * qcom_glink_set_flow_control() - convert a signal cmd to wire format and
+ * transmit
+ * @ept: Rpmsg endpoint for channel.
+ * @enable: True/False - enable or disable flow control
+ * @dst: destination address of the endpoint
+ *
+ * Return: 0 on success or standard Linux error code.
+ */
+static int qcom_glink_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst)
+{
+ struct glink_channel *channel = to_glink_channel(ept);
+ struct qcom_glink *glink = channel->glink;
+ struct glink_msg msg;
+ u32 sigs = 0;
+
+ if (enable)
+ sigs |= NATIVE_DTR_SIG | NATIVE_RTS_SIG;
+
+ msg.cmd = cpu_to_le16(GLINK_CMD_SIGNALS);
+ msg.param1 = cpu_to_le16(channel->lcid);
+ msg.param2 = cpu_to_le32(sigs);
+
+ return qcom_glink_tx(glink, &msg, sizeof(msg), NULL, 0, true);
+}
+
+static int qcom_glink_handle_signals(struct qcom_glink *glink,
+ unsigned int rcid, unsigned int sigs)
+{
+ struct glink_channel *channel;
+ unsigned long flags;
+ bool enable = false;
+
+ spin_lock_irqsave(&glink->idr_lock, flags);
+ channel = idr_find(&glink->rcids, rcid);
+ spin_unlock_irqrestore(&glink->idr_lock, flags);
+ if (!channel) {
+ dev_err(glink->dev, "signal for non-existing channel\n");
+ return -EINVAL;
+ }
+
+ if (!channel->ept.flow_cb)
+ return 0;
+
+ if (sigs & (NATIVE_DSR_SIG | NATIVE_CTS_SIG))
+ enable = true;
+
+ channel->ept.flow_cb(channel->ept.rpdev, channel->ept.priv, enable);
+
+ return 0;
+}
+
void qcom_glink_native_rx(struct qcom_glink *glink)
{
struct glink_msg msg;
@@ -1075,6 +1134,10 @@ void qcom_glink_native_rx(struct qcom_glink *glink)
qcom_glink_handle_intent_req_ack(glink, param1, param2);
qcom_glink_rx_advance(glink, ALIGN(sizeof(msg), 8));
break;
+ case GLINK_CMD_SIGNALS:
+ qcom_glink_handle_signals(glink, param1, param2);
+ qcom_glink_rx_advance(glink, ALIGN(sizeof(msg), 8));
+ break;
default:
dev_err(glink->dev, "unhandled rx cmd: %d\n", cmd);
ret = -EINVAL;
@@ -1449,6 +1512,7 @@ static const struct rpmsg_endpoint_ops glink_endpoint_ops = {
.sendto = qcom_glink_sendto,
.trysend = qcom_glink_trysend,
.trysendto = qcom_glink_trysendto,
+ .set_flow_control = qcom_glink_set_flow_control,
};
static void qcom_glink_rpdev_release(struct device *dev)
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
Add RPMSG_GET_OUTGOING_FLOWCONTROL and RPMSG_SET_INCOMING_FLOWCONTROL
IOCTL support for rpmsg char device nodes to get/set the low level
transport signals.
Signed-off-by: Chris Lew <[email protected]>
Signed-off-by: Deepak Kumar Singh <[email protected]>
Signed-off-by: Sarannya S <[email protected]>
---
drivers/rpmsg/rpmsg_char.c | 53 ++++++++++++++++++++++++++++++++++++++++------
include/uapi/linux/rpmsg.h | 11 +++++++++-
2 files changed, 57 insertions(+), 7 deletions(-)
diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index a271fce..97f80f4 100644
--- a/drivers/rpmsg/rpmsg_char.c
+++ b/drivers/rpmsg/rpmsg_char.c
@@ -23,6 +23,7 @@
#include <linux/rpmsg.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
+#include <linux/termios.h>
#include <linux/uaccess.h>
#include <uapi/linux/rpmsg.h>
@@ -68,6 +69,8 @@ struct rpmsg_eptdev {
struct sk_buff_head queue;
wait_queue_head_t readq;
+ bool remote_flow;
+ bool remote_flow_updated;
};
int rpmsg_chrdev_eptdev_destroy(struct device *dev, void *data)
@@ -116,6 +119,18 @@ static int rpmsg_ept_cb(struct rpmsg_device *rpdev, void *buf, int len,
return 0;
}
+static int rpmsg_ept_flow_cb(struct rpmsg_device *rpdev, void *priv, bool enable)
+{
+ struct rpmsg_eptdev *eptdev = priv;
+
+ eptdev->remote_flow = enable;
+ eptdev->remote_flow_updated = true;
+
+ wake_up_interruptible(&eptdev->readq);
+
+ return 0;
+}
+
static int rpmsg_eptdev_open(struct inode *inode, struct file *filp)
{
struct rpmsg_eptdev *eptdev = cdev_to_eptdev(inode->i_cdev);
@@ -152,6 +167,7 @@ static int rpmsg_eptdev_open(struct inode *inode, struct file *filp)
return -EINVAL;
}
+ ept->flow_cb = rpmsg_ept_flow_cb;
eptdev->ept = ept;
filp->private_data = eptdev;
mutex_unlock(&eptdev->ept_lock);
@@ -172,6 +188,7 @@ static int rpmsg_eptdev_release(struct inode *inode, struct file *filp)
eptdev->ept = NULL;
}
mutex_unlock(&eptdev->ept_lock);
+ eptdev->remote_flow_updated = false;
/* Discard all SKBs */
skb_queue_purge(&eptdev->queue);
@@ -285,6 +302,9 @@ static __poll_t rpmsg_eptdev_poll(struct file *filp, poll_table *wait)
if (!skb_queue_empty(&eptdev->queue))
mask |= EPOLLIN | EPOLLRDNORM;
+ if (eptdev->remote_flow_updated)
+ mask |= EPOLLPRI;
+
mutex_lock(&eptdev->ept_lock);
mask |= rpmsg_poll(eptdev->ept, filp, wait);
mutex_unlock(&eptdev->ept_lock);
@@ -297,14 +317,35 @@ static long rpmsg_eptdev_ioctl(struct file *fp, unsigned int cmd,
{
struct rpmsg_eptdev *eptdev = fp->private_data;
- if (cmd != RPMSG_DESTROY_EPT_IOCTL)
- return -EINVAL;
+ bool set;
+ u32 val;
+ int ret;
- /* Don't allow to destroy a default endpoint. */
- if (eptdev->default_ept)
- return -EINVAL;
+ switch (cmd) {
+ case RPMSG_GET_OUTGOING_FLOWCONTROL:
+ eptdev->remote_flow_updated = false;
+ ret = put_user(eptdev->remote_flow, (int __user *)arg);
+ break;
+ case RPMSG_SET_INCOMING_FLOWCONTROL:
+ ret = get_user(val, (int __user *)arg);
+ if (ret)
+ break;
+ set = !!arg;
+ ret = rpmsg_set_flow_control(eptdev->ept, set);
+ break;
+ case RPMSG_DESTROY_EPT_IOCTL:
+ /* Don't allow to destroy a default endpoint. */
+ if (eptdev->default_ept) {
+ ret = -EINVAL;
+ break;
+ }
+ ret = rpmsg_chrdev_eptdev_destroy(&eptdev->dev, NULL);
+ break;
+ default:
+ ret = -EINVAL;
+ }
- return rpmsg_chrdev_eptdev_destroy(&eptdev->dev, NULL);
+ return ret;
}
static const struct file_operations rpmsg_eptdev_fops = {
diff --git a/include/uapi/linux/rpmsg.h b/include/uapi/linux/rpmsg.h
index 1637e68..c955e27 100644
--- a/include/uapi/linux/rpmsg.h
+++ b/include/uapi/linux/rpmsg.h
@@ -10,7 +10,6 @@
#include <linux/types.h>
#define RPMSG_ADDR_ANY 0xFFFFFFFF
-
/**
* struct rpmsg_endpoint_info - endpoint info representation
* @name: name of service
@@ -43,4 +42,14 @@ struct rpmsg_endpoint_info {
*/
#define RPMSG_RELEASE_DEV_IOCTL _IOW(0xb5, 0x4, struct rpmsg_endpoint_info)
+/**
+ * Set the flow control for the remote rpmsg char device.
+ */
+#define RPMSG_GET_OUTGOING_FLOWCONTROL _IOW(0xb5, 0x5, struct rpmsg_endpoint_info)
+
+/**
+ * Set the flow control for the local rpmsg char device.
+ */
+#define RPMSG_SET_INCOMING_FLOWCONTROL _IOW(0xb5, 0x6, struct rpmsg_endpoint_info)
+
#endif
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
Hi Sarannya,
kernel test robot noticed the following build errors:
[auto build test ERROR on v6.3-rc7]
[also build test ERROR on linus/master next-20230418]
[cannot apply to remoteproc/rpmsg-next]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Sarannya-S/rpmsg-core-Add-signal-API-support/20230419-220040
patch link: https://lore.kernel.org/r/1681912409-25248-4-git-send-email-quic_sarannya%40quicinc.com
patch subject: [PATCH V6 3/3] rpmsg: char: Add RPMSG GET/SET FLOWCONTROL IOCTL support
config: m68k-allyesconfig (https://download.01.org/0day-ci/archive/20230420/[email protected]/config)
compiler: m68k-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/4f765ede8c129f07c522ef4a7c6aee27cb466be6
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Sarannya-S/rpmsg-core-Add-signal-API-support/20230419-220040
git checkout 4f765ede8c129f07c522ef4a7c6aee27cb466be6
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=m68k olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=m68k SHELL=/bin/bash drivers/
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <[email protected]>
| Link: https://lore.kernel.org/oe-kbuild-all/[email protected]/
All error/warnings (new ones prefixed by >>):
drivers/rpmsg/rpmsg_char.c: In function 'rpmsg_eptdev_ioctl':
>> drivers/rpmsg/rpmsg_char.c:334:23: error: too few arguments to function 'rpmsg_set_flow_control'
334 | ret = rpmsg_set_flow_control(eptdev->ept, set);
| ^~~~~~~~~~~~~~~~~~~~~~
In file included from drivers/rpmsg/rpmsg_char.c:23:
include/linux/rpmsg.h:200:5: note: declared here
200 | int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst);
| ^~~~~~~~~~~~~~~~~~~~~~
>> drivers/rpmsg/rpmsg_char.c:321:13: warning: variable 'val' set but not used [-Wunused-but-set-variable]
321 | u32 val;
| ^~~
vim +/rpmsg_set_flow_control +334 drivers/rpmsg/rpmsg_char.c
314
315 static long rpmsg_eptdev_ioctl(struct file *fp, unsigned int cmd,
316 unsigned long arg)
317 {
318 struct rpmsg_eptdev *eptdev = fp->private_data;
319
320 bool set;
> 321 u32 val;
322 int ret;
323
324 switch (cmd) {
325 case RPMSG_GET_OUTGOING_FLOWCONTROL:
326 eptdev->remote_flow_updated = false;
327 ret = put_user(eptdev->remote_flow, (int __user *)arg);
328 break;
329 case RPMSG_SET_INCOMING_FLOWCONTROL:
330 ret = get_user(val, (int __user *)arg);
331 if (ret)
332 break;
333 set = !!arg;
> 334 ret = rpmsg_set_flow_control(eptdev->ept, set);
335 break;
336 case RPMSG_DESTROY_EPT_IOCTL:
337 /* Don't allow to destroy a default endpoint. */
338 if (eptdev->default_ept) {
339 ret = -EINVAL;
340 break;
341 }
342 ret = rpmsg_chrdev_eptdev_destroy(&eptdev->dev, NULL);
343 break;
344 default:
345 ret = -EINVAL;
346 }
347
348 return ret;
349 }
350
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests
On 4/19/2023 6:53 AM, 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..cd71a6a 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(rpmsg_set_flow_control);
Why not EXPORT_SYMBOL_GPL?
---Trilok Soni