Currently the I3C framework limits SCL frequency to FM speed when
dealing with a mixed slow bus, even if all I2C devices are FM+ capable.
The core was also not accounting for I3C speed limitations when
operating in mixed slow mode and was erroneously using FM+ speed as the
max I2C speed when operating in mixed fast mode.
Fixes: 3a379bbcea0a ("i3c: Add core I3C infrastructure")
Signed-off-by: Vitor Soares <[email protected]>
Cc: Boris Brezillon <[email protected]>
Cc: <[email protected]>
Cc: <[email protected]>
---
Changes in v2:
Enhance commit message
Add dev_warn() in case user-defined i2c rate doesn't match LVR constraint
Add dev_warn() in case user-defined i3c rate lower than i2c rate.
drivers/i3c/master.c | 61 +++++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 48 insertions(+), 13 deletions(-)
diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index 5f4bd52..8cd5824 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -91,6 +91,12 @@ void i3c_bus_normaluse_unlock(struct i3c_bus *bus)
up_read(&bus->lock);
}
+static struct i3c_master_controller *
+i3c_bus_to_i3c_master(struct i3c_bus *i3cbus)
+{
+ return container_of(i3cbus, struct i3c_master_controller, bus);
+}
+
static struct i3c_master_controller *dev_to_i3cmaster(struct device *dev)
{
return container_of(dev, struct i3c_master_controller, dev);
@@ -565,20 +571,48 @@ static const struct device_type i3c_masterdev_type = {
.groups = i3c_masterdev_groups,
};
-int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode)
+int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode,
+ unsigned long max_i2c_scl_rate)
{
- i3cbus->mode = mode;
- if (!i3cbus->scl_rate.i3c)
- i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
+ struct i3c_master_controller *master = i3c_bus_to_i3c_master(i3cbus);
- if (!i3cbus->scl_rate.i2c) {
- if (i3cbus->mode == I3C_BUS_MODE_MIXED_SLOW)
- i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_SCL_RATE;
- else
- i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_PLUS_SCL_RATE;
+ i3cbus->mode = mode;
+
+ switch (i3cbus->mode) {
+ case I3C_BUS_MODE_PURE:
+ if (!i3cbus->scl_rate.i3c)
+ i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
+ break;
+ case I3C_BUS_MODE_MIXED_FAST:
+ if (!i3cbus->scl_rate.i3c)
+ i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
+ if (!i3cbus->scl_rate.i2c)
+ i3cbus->scl_rate.i2c = max_i2c_scl_rate;
+ break;
+ case I3C_BUS_MODE_MIXED_SLOW:
+ if (!i3cbus->scl_rate.i2c)
+ i3cbus->scl_rate.i2c = max_i2c_scl_rate;
+ if (!i3cbus->scl_rate.i3c ||
+ i3cbus->scl_rate.i3c > i3cbus->scl_rate.i2c)
+ i3cbus->scl_rate.i3c = i3cbus->scl_rate.i2c;
+ break;
+ default:
+ return -EINVAL;
}
+ if (i3cbus->scl_rate.i3c < i3cbus->scl_rate.i2c)
+ dev_warn(&master->dev,
+ "i3c-scl-hz=%ld lower than i2c-scl-hz=%ld\n",
+ i3cbus->scl_rate.i3c, i3cbus->scl_rate.i2c);
+
+ if (i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_SCL_RATE &&
+ i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_PLUS_SCL_RATE &&
+ i3cbus->mode != I3C_BUS_MODE_PURE)
+ dev_warn(&master->dev,
+ "i2c-scl-hz=%ld not defined according MIPI I3C spec\n"
+ , i3cbus->scl_rate.i2c);
+
/*
* I3C/I2C frequency may have been overridden, check that user-provided
* values are not exceeding max possible frequency.
@@ -1966,9 +2000,6 @@ of_i3c_master_add_i2c_boardinfo(struct i3c_master_controller *master,
/* LVR is encoded in reg[2]. */
boardinfo->lvr = reg[2];
- if (boardinfo->lvr & I3C_LVR_I2C_FM_MODE)
- master->bus.scl_rate.i2c = I3C_BUS_I2C_FM_SCL_RATE;
-
list_add_tail(&boardinfo->node, &master->boardinfo.i2c);
of_node_get(node);
@@ -2417,6 +2448,7 @@ int i3c_master_register(struct i3c_master_controller *master,
const struct i3c_master_controller_ops *ops,
bool secondary)
{
+ unsigned long i2c_scl_rate = I3C_BUS_I2C_FM_PLUS_SCL_RATE;
struct i3c_bus *i3cbus = i3c_master_get_bus(master);
enum i3c_bus_mode mode = I3C_BUS_MODE_PURE;
struct i2c_dev_boardinfo *i2cbi;
@@ -2466,9 +2498,12 @@ int i3c_master_register(struct i3c_master_controller *master,
ret = -EINVAL;
goto err_put_dev;
}
+
+ if (i2cbi->lvr & I3C_LVR_I2C_FM_MODE)
+ i2c_scl_rate = I3C_BUS_I2C_FM_SCL_RATE;
}
- ret = i3c_bus_set_mode(i3cbus, mode);
+ ret = i3c_bus_set_mode(i3cbus, mode, i2c_scl_rate);
if (ret)
goto err_put_dev;
--
2.7.4
On Thu, 6 Jun 2019 16:00:01 +0200
Vitor Soares <[email protected]> wrote:
> Currently the I3C framework limits SCL frequency to FM speed when
> dealing with a mixed slow bus, even if all I2C devices are FM+ capable.
>
> The core was also not accounting for I3C speed limitations when
> operating in mixed slow mode and was erroneously using FM+ speed as the
> max I2C speed when operating in mixed fast mode.
>
> Fixes: 3a379bbcea0a ("i3c: Add core I3C infrastructure")
> Signed-off-by: Vitor Soares <[email protected]>
> Cc: Boris Brezillon <[email protected]>
> Cc: <[email protected]>
> Cc: <[email protected]>
> ---
> Changes in v2:
> Enhance commit message
> Add dev_warn() in case user-defined i2c rate doesn't match LVR constraint
> Add dev_warn() in case user-defined i3c rate lower than i2c rate.
>
> drivers/i3c/master.c | 61 +++++++++++++++++++++++++++++++++++++++++-----------
> 1 file changed, 48 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> index 5f4bd52..8cd5824 100644
> --- a/drivers/i3c/master.c
> +++ b/drivers/i3c/master.c
> @@ -91,6 +91,12 @@ void i3c_bus_normaluse_unlock(struct i3c_bus *bus)
> up_read(&bus->lock);
> }
>
> +static struct i3c_master_controller *
> +i3c_bus_to_i3c_master(struct i3c_bus *i3cbus)
> +{
> + return container_of(i3cbus, struct i3c_master_controller, bus);
> +}
> +
> static struct i3c_master_controller *dev_to_i3cmaster(struct device *dev)
> {
> return container_of(dev, struct i3c_master_controller, dev);
> @@ -565,20 +571,48 @@ static const struct device_type i3c_masterdev_type = {
> .groups = i3c_masterdev_groups,
> };
>
> -int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode)
> +int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode,
> + unsigned long max_i2c_scl_rate)
> {
> - i3cbus->mode = mode;
>
> - if (!i3cbus->scl_rate.i3c)
> - i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> + struct i3c_master_controller *master = i3c_bus_to_i3c_master(i3cbus);
>
> - if (!i3cbus->scl_rate.i2c) {
> - if (i3cbus->mode == I3C_BUS_MODE_MIXED_SLOW)
> - i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_SCL_RATE;
> - else
> - i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_PLUS_SCL_RATE;
> + i3cbus->mode = mode;
> +
> + switch (i3cbus->mode) {
> + case I3C_BUS_MODE_PURE:
> + if (!i3cbus->scl_rate.i3c)
> + i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> + break;
> + case I3C_BUS_MODE_MIXED_FAST:
> + if (!i3cbus->scl_rate.i3c)
> + i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> + if (!i3cbus->scl_rate.i2c)
> + i3cbus->scl_rate.i2c = max_i2c_scl_rate;
> + break;
> + case I3C_BUS_MODE_MIXED_SLOW:
> + if (!i3cbus->scl_rate.i2c)
> + i3cbus->scl_rate.i2c = max_i2c_scl_rate;
> + if (!i3cbus->scl_rate.i3c ||
> + i3cbus->scl_rate.i3c > i3cbus->scl_rate.i2c)
> + i3cbus->scl_rate.i3c = i3cbus->scl_rate.i2c;
> + break;
> + default:
> + return -EINVAL;
> }
>
> + if (i3cbus->scl_rate.i3c < i3cbus->scl_rate.i2c)
> + dev_warn(&master->dev,
> + "i3c-scl-hz=%ld lower than i2c-scl-hz=%ld\n",
> + i3cbus->scl_rate.i3c, i3cbus->scl_rate.i2c);
> +
> + if (i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_SCL_RATE &&
> + i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_PLUS_SCL_RATE &&
> + i3cbus->mode != I3C_BUS_MODE_PURE)
If you are so strict, there's clearly no point exposing an i2c-scl-hz
property. I'm still not convinced having an i2c rate that's slower than
what the I2C/I3C spec defines as the *typical* rate is a bad thing, just
like I'm not convinced having an I3C rate that's slower than the I2C
one is a problem (it's definitely a weird situation, but there's nothing
preventing that in the spec).
> + dev_warn(&master->dev,
> + "i2c-scl-hz=%ld not defined according MIPI I3C spec\n"
> + , i3cbus->scl_rate.i2c);
The comma should be on the previous line.
> +
> /*
> * I3C/I2C frequency may have been overridden, check that user-provided
> * values are not exceeding max possible frequency.
> @@ -1966,9 +2000,6 @@ of_i3c_master_add_i2c_boardinfo(struct i3c_master_controller *master,
> /* LVR is encoded in reg[2]. */
> boardinfo->lvr = reg[2];
>
> - if (boardinfo->lvr & I3C_LVR_I2C_FM_MODE)
> - master->bus.scl_rate.i2c = I3C_BUS_I2C_FM_SCL_RATE;
> -
> list_add_tail(&boardinfo->node, &master->boardinfo.i2c);
> of_node_get(node);
>
> @@ -2417,6 +2448,7 @@ int i3c_master_register(struct i3c_master_controller *master,
> const struct i3c_master_controller_ops *ops,
> bool secondary)
> {
> + unsigned long i2c_scl_rate = I3C_BUS_I2C_FM_PLUS_SCL_RATE;
> struct i3c_bus *i3cbus = i3c_master_get_bus(master);
> enum i3c_bus_mode mode = I3C_BUS_MODE_PURE;
> struct i2c_dev_boardinfo *i2cbi;
> @@ -2466,9 +2498,12 @@ int i3c_master_register(struct i3c_master_controller *master,
> ret = -EINVAL;
> goto err_put_dev;
> }
> +
> + if (i2cbi->lvr & I3C_LVR_I2C_FM_MODE)
> + i2c_scl_rate = I3C_BUS_I2C_FM_SCL_RATE;
> }
>
> - ret = i3c_bus_set_mode(i3cbus, mode);
> + ret = i3c_bus_set_mode(i3cbus, mode, i2c_scl_rate);
> if (ret)
> goto err_put_dev;
>
From: Boris Brezillon <[email protected]>
Date: Thu, Jun 06, 2019 at 15:18:44
> On Thu, 6 Jun 2019 16:00:01 +0200
> Vitor Soares <[email protected]> wrote:
>
> > Currently the I3C framework limits SCL frequency to FM speed when
> > dealing with a mixed slow bus, even if all I2C devices are FM+ capable.
> >
> > The core was also not accounting for I3C speed limitations when
> > operating in mixed slow mode and was erroneously using FM+ speed as the
> > max I2C speed when operating in mixed fast mode.
> >
> > Fixes: 3a379bbcea0a ("i3c: Add core I3C infrastructure")
> > Signed-off-by: Vitor Soares <[email protected]>
> > Cc: Boris Brezillon <[email protected]>
> > Cc: <[email protected]>
> > Cc: <[email protected]>
> > ---
> > Changes in v2:
> > Enhance commit message
> > Add dev_warn() in case user-defined i2c rate doesn't match LVR constraint
> > Add dev_warn() in case user-defined i3c rate lower than i2c rate.
> >
> > drivers/i3c/master.c | 61 +++++++++++++++++++++++++++++++++++++++++-----------
> > 1 file changed, 48 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> > index 5f4bd52..8cd5824 100644
> > --- a/drivers/i3c/master.c
> > +++ b/drivers/i3c/master.c
> > @@ -91,6 +91,12 @@ void i3c_bus_normaluse_unlock(struct i3c_bus *bus)
> > up_read(&bus->lock);
> > }
> >
> > +static struct i3c_master_controller *
> > +i3c_bus_to_i3c_master(struct i3c_bus *i3cbus)
> > +{
> > + return container_of(i3cbus, struct i3c_master_controller, bus);
> > +}
> > +
> > static struct i3c_master_controller *dev_to_i3cmaster(struct device *dev)
> > {
> > return container_of(dev, struct i3c_master_controller, dev);
> > @@ -565,20 +571,48 @@ static const struct device_type i3c_masterdev_type = {
> > .groups = i3c_masterdev_groups,
> > };
> >
> > -int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode)
> > +int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode,
> > + unsigned long max_i2c_scl_rate)
> > {
> > - i3cbus->mode = mode;
> >
> > - if (!i3cbus->scl_rate.i3c)
> > - i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> > + struct i3c_master_controller *master = i3c_bus_to_i3c_master(i3cbus);
> >
> > - if (!i3cbus->scl_rate.i2c) {
> > - if (i3cbus->mode == I3C_BUS_MODE_MIXED_SLOW)
> > - i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_SCL_RATE;
> > - else
> > - i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_PLUS_SCL_RATE;
> > + i3cbus->mode = mode;
> > +
> > + switch (i3cbus->mode) {
> > + case I3C_BUS_MODE_PURE:
> > + if (!i3cbus->scl_rate.i3c)
> > + i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> > + break;
> > + case I3C_BUS_MODE_MIXED_FAST:
> > + if (!i3cbus->scl_rate.i3c)
> > + i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> > + if (!i3cbus->scl_rate.i2c)
> > + i3cbus->scl_rate.i2c = max_i2c_scl_rate;
> > + break;
> > + case I3C_BUS_MODE_MIXED_SLOW:
> > + if (!i3cbus->scl_rate.i2c)
> > + i3cbus->scl_rate.i2c = max_i2c_scl_rate;
> > + if (!i3cbus->scl_rate.i3c ||
> > + i3cbus->scl_rate.i3c > i3cbus->scl_rate.i2c)
> > + i3cbus->scl_rate.i3c = i3cbus->scl_rate.i2c;
> > + break;
> > + default:
> > + return -EINVAL;
> > }
> >
> > + if (i3cbus->scl_rate.i3c < i3cbus->scl_rate.i2c)
> > + dev_warn(&master->dev,
> > + "i3c-scl-hz=%ld lower than i2c-scl-hz=%ld\n",
> > + i3cbus->scl_rate.i3c, i3cbus->scl_rate.i2c);
> > +
> > + if (i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_SCL_RATE &&
> > + i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_PLUS_SCL_RATE &&
> > + i3cbus->mode != I3C_BUS_MODE_PURE)
>
> If you are so strict, there's clearly no point exposing an i2c-scl-hz
> property. I'm still not convinced having an i2c rate that's slower than
> what the I2C/I3C spec defines as the *typical* rate is a bad thing,
I'm not been strictive, I just inform the user about that case.
> just
> like I'm not convinced having an I3C rate that's slower than the I2C
> one is a problem (it's definitely a weird situation, but there's nothing
> preventing that in the spec).
You agree that there is no point for case where i3c rate < i2c rate yet
you are not convinced.
Do you thing that will be users for this case?
Anyway, this isn't a high requirement for me. The all point of this patch
is to introduce the limited bus configuration.
>
> > + dev_warn(&master->dev,
> > + "i2c-scl-hz=%ld not defined according MIPI I3C spec\n"
> > + , i3cbus->scl_rate.i2c);
>
> The comma should be on the previous line.
>
> > +
> > /*
> > * I3C/I2C frequency may have been overridden, check that user-provided
> > * values are not exceeding max possible frequency.
> > @@ -1966,9 +2000,6 @@ of_i3c_master_add_i2c_boardinfo(struct i3c_master_controller *master,
> > /* LVR is encoded in reg[2]. */
> > boardinfo->lvr = reg[2];
> >
> > - if (boardinfo->lvr & I3C_LVR_I2C_FM_MODE)
> > - master->bus.scl_rate.i2c = I3C_BUS_I2C_FM_SCL_RATE;
> > -
> > list_add_tail(&boardinfo->node, &master->boardinfo.i2c);
> > of_node_get(node);
> >
> > @@ -2417,6 +2448,7 @@ int i3c_master_register(struct i3c_master_controller *master,
> > const struct i3c_master_controller_ops *ops,
> > bool secondary)
> > {
> > + unsigned long i2c_scl_rate = I3C_BUS_I2C_FM_PLUS_SCL_RATE;
> > struct i3c_bus *i3cbus = i3c_master_get_bus(master);
> > enum i3c_bus_mode mode = I3C_BUS_MODE_PURE;
> > struct i2c_dev_boardinfo *i2cbi;
> > @@ -2466,9 +2498,12 @@ int i3c_master_register(struct i3c_master_controller *master,
> > ret = -EINVAL;
> > goto err_put_dev;
> > }
> > +
> > + if (i2cbi->lvr & I3C_LVR_I2C_FM_MODE)
> > + i2c_scl_rate = I3C_BUS_I2C_FM_SCL_RATE;
> > }
> >
> > - ret = i3c_bus_set_mode(i3cbus, mode);
> > + ret = i3c_bus_set_mode(i3cbus, mode, i2c_scl_rate);
> > if (ret)
> > goto err_put_dev;
> >
Best regards,
Vitor Soares
On Thu, 6 Jun 2019 17:16:55 +0000
Vitor Soares <[email protected]> wrote:
> From: Boris Brezillon <[email protected]>
> Date: Thu, Jun 06, 2019 at 15:18:44
>
> > On Thu, 6 Jun 2019 16:00:01 +0200
> > Vitor Soares <[email protected]> wrote:
> >
> > > Currently the I3C framework limits SCL frequency to FM speed when
> > > dealing with a mixed slow bus, even if all I2C devices are FM+ capable.
> > >
> > > The core was also not accounting for I3C speed limitations when
> > > operating in mixed slow mode and was erroneously using FM+ speed as the
> > > max I2C speed when operating in mixed fast mode.
> > >
> > > Fixes: 3a379bbcea0a ("i3c: Add core I3C infrastructure")
> > > Signed-off-by: Vitor Soares <[email protected]>
> > > Cc: Boris Brezillon <[email protected]>
> > > Cc: <[email protected]>
> > > Cc: <[email protected]>
> > > ---
> > > Changes in v2:
> > > Enhance commit message
> > > Add dev_warn() in case user-defined i2c rate doesn't match LVR constraint
> > > Add dev_warn() in case user-defined i3c rate lower than i2c rate.
> > >
> > > drivers/i3c/master.c | 61 +++++++++++++++++++++++++++++++++++++++++-----------
> > > 1 file changed, 48 insertions(+), 13 deletions(-)
> > >
> > > diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> > > index 5f4bd52..8cd5824 100644
> > > --- a/drivers/i3c/master.c
> > > +++ b/drivers/i3c/master.c
> > > @@ -91,6 +91,12 @@ void i3c_bus_normaluse_unlock(struct i3c_bus *bus)
> > > up_read(&bus->lock);
> > > }
> > >
> > > +static struct i3c_master_controller *
> > > +i3c_bus_to_i3c_master(struct i3c_bus *i3cbus)
> > > +{
> > > + return container_of(i3cbus, struct i3c_master_controller, bus);
> > > +}
> > > +
> > > static struct i3c_master_controller *dev_to_i3cmaster(struct device *dev)
> > > {
> > > return container_of(dev, struct i3c_master_controller, dev);
> > > @@ -565,20 +571,48 @@ static const struct device_type i3c_masterdev_type = {
> > > .groups = i3c_masterdev_groups,
> > > };
> > >
> > > -int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode)
> > > +int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode,
> > > + unsigned long max_i2c_scl_rate)
> > > {
> > > - i3cbus->mode = mode;
> > >
> > > - if (!i3cbus->scl_rate.i3c)
> > > - i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> > > + struct i3c_master_controller *master = i3c_bus_to_i3c_master(i3cbus);
> > >
> > > - if (!i3cbus->scl_rate.i2c) {
> > > - if (i3cbus->mode == I3C_BUS_MODE_MIXED_SLOW)
> > > - i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_SCL_RATE;
> > > - else
> > > - i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_PLUS_SCL_RATE;
> > > + i3cbus->mode = mode;
> > > +
> > > + switch (i3cbus->mode) {
> > > + case I3C_BUS_MODE_PURE:
> > > + if (!i3cbus->scl_rate.i3c)
> > > + i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> > > + break;
> > > + case I3C_BUS_MODE_MIXED_FAST:
> > > + if (!i3cbus->scl_rate.i3c)
> > > + i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> > > + if (!i3cbus->scl_rate.i2c)
> > > + i3cbus->scl_rate.i2c = max_i2c_scl_rate;
> > > + break;
> > > + case I3C_BUS_MODE_MIXED_SLOW:
> > > + if (!i3cbus->scl_rate.i2c)
> > > + i3cbus->scl_rate.i2c = max_i2c_scl_rate;
> > > + if (!i3cbus->scl_rate.i3c ||
> > > + i3cbus->scl_rate.i3c > i3cbus->scl_rate.i2c)
> > > + i3cbus->scl_rate.i3c = i3cbus->scl_rate.i2c;
> > > + break;
> > > + default:
> > > + return -EINVAL;
> > > }
> > >
> > > + if (i3cbus->scl_rate.i3c < i3cbus->scl_rate.i2c)
> > > + dev_warn(&master->dev,
> > > + "i3c-scl-hz=%ld lower than i2c-scl-hz=%ld\n",
> > > + i3cbus->scl_rate.i3c, i3cbus->scl_rate.i2c);
> > > +
> > > + if (i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_SCL_RATE &&
> > > + i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_PLUS_SCL_RATE &&
> > > + i3cbus->mode != I3C_BUS_MODE_PURE)
> >
> > If you are so strict, there's clearly no point exposing an i2c-scl-hz
> > property. I'm still not convinced having an i2c rate that's slower than
> > what the I2C/I3C spec defines as the *typical* rate is a bad thing,
>
> I'm not been strictive, I just inform the user about that case.
Then use dev_debug() and don't make the trace conditional on
i2c_rate != typical_rate. The only case where we should warn users
is i2c_rate > typical_rate, because that might lead to malfunctions.
>
> > just
> > like I'm not convinced having an I3C rate that's slower than the I2C
> > one is a problem (it's definitely a weird situation, but there's nothing
> > preventing that in the spec).
>
> You agree that there is no point for case where i3c rate < i2c rate yet
> you are not convinced.
I didn't say that, there might be use cases where one wants to slow
down the I3C bus to be able to probe it or use a slower rate when
things do not work properly. It's rather unlikely to happen, but I
don't think it deserves a warning message when that's the case.
> Do you thing that will be users for this case?
>
> Anyway, this isn't a high requirement for me. The all point of this patch
> is to introduce the limited bus configuration.
And yet, you keep insisting (and ignoring my feedback) on that point :P.
From: Boris Brezillon <[email protected]>
Date: Thu, Jun 06, 2019 at 18:35:40
> On Thu, 6 Jun 2019 17:16:55 +0000
> Vitor Soares <[email protected]> wrote:
>
> > From: Boris Brezillon <[email protected]>
> > Date: Thu, Jun 06, 2019 at 15:18:44
> >
> > > On Thu, 6 Jun 2019 16:00:01 +0200
> > > Vitor Soares <[email protected]> wrote:
> > >
> > > > Currently the I3C framework limits SCL frequency to FM speed when
> > > > dealing with a mixed slow bus, even if all I2C devices are FM+ capable.
> > > >
> > > > The core was also not accounting for I3C speed limitations when
> > > > operating in mixed slow mode and was erroneously using FM+ speed as the
> > > > max I2C speed when operating in mixed fast mode.
> > > >
> > > > Fixes: 3a379bbcea0a ("i3c: Add core I3C infrastructure")
> > > > Signed-off-by: Vitor Soares <[email protected]>
> > > > Cc: Boris Brezillon <[email protected]>
> > > > Cc: <[email protected]>
> > > > Cc: <[email protected]>
> > > > ---
> > > > Changes in v2:
> > > > Enhance commit message
> > > > Add dev_warn() in case user-defined i2c rate doesn't match LVR constraint
> > > > Add dev_warn() in case user-defined i3c rate lower than i2c rate.
> > > >
> > > > drivers/i3c/master.c | 61 +++++++++++++++++++++++++++++++++++++++++-----------
> > > > 1 file changed, 48 insertions(+), 13 deletions(-)
> > > >
> > > > diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> > > > index 5f4bd52..8cd5824 100644
> > > > --- a/drivers/i3c/master.c
> > > > +++ b/drivers/i3c/master.c
> > > > @@ -91,6 +91,12 @@ void i3c_bus_normaluse_unlock(struct i3c_bus *bus)
> > > > up_read(&bus->lock);
> > > > }
> > > >
> > > > +static struct i3c_master_controller *
> > > > +i3c_bus_to_i3c_master(struct i3c_bus *i3cbus)
> > > > +{
> > > > + return container_of(i3cbus, struct i3c_master_controller, bus);
> > > > +}
> > > > +
> > > > static struct i3c_master_controller *dev_to_i3cmaster(struct device *dev)
> > > > {
> > > > return container_of(dev, struct i3c_master_controller, dev);
> > > > @@ -565,20 +571,48 @@ static const struct device_type i3c_masterdev_type = {
> > > > .groups = i3c_masterdev_groups,
> > > > };
> > > >
> > > > -int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode)
> > > > +int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode,
> > > > + unsigned long max_i2c_scl_rate)
> > > > {
> > > > - i3cbus->mode = mode;
> > > >
> > > > - if (!i3cbus->scl_rate.i3c)
> > > > - i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> > > > + struct i3c_master_controller *master = i3c_bus_to_i3c_master(i3cbus);
> > > >
> > > > - if (!i3cbus->scl_rate.i2c) {
> > > > - if (i3cbus->mode == I3C_BUS_MODE_MIXED_SLOW)
> > > > - i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_SCL_RATE;
> > > > - else
> > > > - i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_PLUS_SCL_RATE;
> > > > + i3cbus->mode = mode;
> > > > +
> > > > + switch (i3cbus->mode) {
> > > > + case I3C_BUS_MODE_PURE:
> > > > + if (!i3cbus->scl_rate.i3c)
> > > > + i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> > > > + break;
> > > > + case I3C_BUS_MODE_MIXED_FAST:
> > > > + if (!i3cbus->scl_rate.i3c)
> > > > + i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> > > > + if (!i3cbus->scl_rate.i2c)
> > > > + i3cbus->scl_rate.i2c = max_i2c_scl_rate;
> > > > + break;
> > > > + case I3C_BUS_MODE_MIXED_SLOW:
> > > > + if (!i3cbus->scl_rate.i2c)
> > > > + i3cbus->scl_rate.i2c = max_i2c_scl_rate;
> > > > + if (!i3cbus->scl_rate.i3c ||
> > > > + i3cbus->scl_rate.i3c > i3cbus->scl_rate.i2c)
> > > > + i3cbus->scl_rate.i3c = i3cbus->scl_rate.i2c;
> > > > + break;
> > > > + default:
> > > > + return -EINVAL;
> > > > }
> > > >
> > > > + if (i3cbus->scl_rate.i3c < i3cbus->scl_rate.i2c)
> > > > + dev_warn(&master->dev,
> > > > + "i3c-scl-hz=%ld lower than i2c-scl-hz=%ld\n",
> > > > + i3cbus->scl_rate.i3c, i3cbus->scl_rate.i2c);
> > > > +
> > > > + if (i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_SCL_RATE &&
> > > > + i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_PLUS_SCL_RATE &&
> > > > + i3cbus->mode != I3C_BUS_MODE_PURE)
> > >
> > > If you are so strict, there's clearly no point exposing an i2c-scl-hz
> > > property. I'm still not convinced having an i2c rate that's slower than
> > > what the I2C/I3C spec defines as the *typical* rate is a bad thing,
> >
> > I'm not been strictive, I just inform the user about that case.
>
> Then use dev_debug() and don't make the trace conditional on
> i2c_rate != typical_rate.
Ok. I will change to dev_debug().
> The only case where we should warn users
> is i2c_rate > typical_rate, because that might lead to malfunctions.
Can you explain why?
>
> >
> > > just
> > > like I'm not convinced having an I3C rate that's slower than the I2C
> > > one is a problem (it's definitely a weird situation, but there's nothing
> > > preventing that in the spec).
> >
> > You agree that there is no point for case where i3c rate < i2c rate yet
> > you are not convinced.
>
> I didn't say that, there might be use cases where one wants to slow
> down the I3C bus to be able to probe it or use a slower rate when
> things do not work properly. It's rather unlikely to happen, but I
> don't think it deserves a warning message when that's the case.
>
> > Do you thing that will be users for this case?
> >
> > Anyway, this isn't a high requirement for me. The all point of this patch
> > is to introduce the limited bus configuration.
>
> And yet, you keep insisting (and ignoring my feedback) on that point :P.
If you check the previous version you see that I'm trying to follow ????
I will change the dev_warn() to dev_dbg() due the trace is indeed too
much.
Best regards,
Vitor Soares
On Thu, 6 Jun 2019 18:08:11 +0000
Vitor Soares <[email protected]> wrote:
> From: Boris Brezillon <[email protected]>
> Date: Thu, Jun 06, 2019 at 18:35:40
>
> > On Thu, 6 Jun 2019 17:16:55 +0000
> > Vitor Soares <[email protected]> wrote:
> >
> > > From: Boris Brezillon <[email protected]>
> > > Date: Thu, Jun 06, 2019 at 15:18:44
> > >
> > > > On Thu, 6 Jun 2019 16:00:01 +0200
> > > > Vitor Soares <[email protected]> wrote:
> > > >
> > > > > Currently the I3C framework limits SCL frequency to FM speed when
> > > > > dealing with a mixed slow bus, even if all I2C devices are FM+ capable.
> > > > >
> > > > > The core was also not accounting for I3C speed limitations when
> > > > > operating in mixed slow mode and was erroneously using FM+ speed as the
> > > > > max I2C speed when operating in mixed fast mode.
> > > > >
> > > > > Fixes: 3a379bbcea0a ("i3c: Add core I3C infrastructure")
> > > > > Signed-off-by: Vitor Soares <[email protected]>
> > > > > Cc: Boris Brezillon <[email protected]>
> > > > > Cc: <[email protected]>
> > > > > Cc: <[email protected]>
> > > > > ---
> > > > > Changes in v2:
> > > > > Enhance commit message
> > > > > Add dev_warn() in case user-defined i2c rate doesn't match LVR constraint
> > > > > Add dev_warn() in case user-defined i3c rate lower than i2c rate.
> > > > >
> > > > > drivers/i3c/master.c | 61 +++++++++++++++++++++++++++++++++++++++++-----------
> > > > > 1 file changed, 48 insertions(+), 13 deletions(-)
> > > > >
> > > > > diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> > > > > index 5f4bd52..8cd5824 100644
> > > > > --- a/drivers/i3c/master.c
> > > > > +++ b/drivers/i3c/master.c
> > > > > @@ -91,6 +91,12 @@ void i3c_bus_normaluse_unlock(struct i3c_bus *bus)
> > > > > up_read(&bus->lock);
> > > > > }
> > > > >
> > > > > +static struct i3c_master_controller *
> > > > > +i3c_bus_to_i3c_master(struct i3c_bus *i3cbus)
> > > > > +{
> > > > > + return container_of(i3cbus, struct i3c_master_controller, bus);
> > > > > +}
> > > > > +
> > > > > static struct i3c_master_controller *dev_to_i3cmaster(struct device *dev)
> > > > > {
> > > > > return container_of(dev, struct i3c_master_controller, dev);
> > > > > @@ -565,20 +571,48 @@ static const struct device_type i3c_masterdev_type = {
> > > > > .groups = i3c_masterdev_groups,
> > > > > };
> > > > >
> > > > > -int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode)
> > > > > +int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode,
> > > > > + unsigned long max_i2c_scl_rate)
> > > > > {
> > > > > - i3cbus->mode = mode;
> > > > >
> > > > > - if (!i3cbus->scl_rate.i3c)
> > > > > - i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> > > > > + struct i3c_master_controller *master = i3c_bus_to_i3c_master(i3cbus);
> > > > >
> > > > > - if (!i3cbus->scl_rate.i2c) {
> > > > > - if (i3cbus->mode == I3C_BUS_MODE_MIXED_SLOW)
> > > > > - i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_SCL_RATE;
> > > > > - else
> > > > > - i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_PLUS_SCL_RATE;
> > > > > + i3cbus->mode = mode;
> > > > > +
> > > > > + switch (i3cbus->mode) {
> > > > > + case I3C_BUS_MODE_PURE:
> > > > > + if (!i3cbus->scl_rate.i3c)
> > > > > + i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> > > > > + break;
> > > > > + case I3C_BUS_MODE_MIXED_FAST:
> > > > > + if (!i3cbus->scl_rate.i3c)
> > > > > + i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> > > > > + if (!i3cbus->scl_rate.i2c)
> > > > > + i3cbus->scl_rate.i2c = max_i2c_scl_rate;
> > > > > + break;
> > > > > + case I3C_BUS_MODE_MIXED_SLOW:
> > > > > + if (!i3cbus->scl_rate.i2c)
> > > > > + i3cbus->scl_rate.i2c = max_i2c_scl_rate;
> > > > > + if (!i3cbus->scl_rate.i3c ||
> > > > > + i3cbus->scl_rate.i3c > i3cbus->scl_rate.i2c)
> > > > > + i3cbus->scl_rate.i3c = i3cbus->scl_rate.i2c;
> > > > > + break;
> > > > > + default:
> > > > > + return -EINVAL;
> > > > > }
> > > > >
> > > > > + if (i3cbus->scl_rate.i3c < i3cbus->scl_rate.i2c)
> > > > > + dev_warn(&master->dev,
> > > > > + "i3c-scl-hz=%ld lower than i2c-scl-hz=%ld\n",
> > > > > + i3cbus->scl_rate.i3c, i3cbus->scl_rate.i2c);
> > > > > +
> > > > > + if (i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_SCL_RATE &&
> > > > > + i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_PLUS_SCL_RATE &&
> > > > > + i3cbus->mode != I3C_BUS_MODE_PURE)
> > > >
> > > > If you are so strict, there's clearly no point exposing an i2c-scl-hz
> > > > property. I'm still not convinced having an i2c rate that's slower than
> > > > what the I2C/I3C spec defines as the *typical* rate is a bad thing,
> > >
> > > I'm not been strictive, I just inform the user about that case.
> >
> > Then use dev_debug() and don't make the trace conditional on
> > i2c_rate != typical_rate.
>
> Ok. I will change to dev_debug().
>
> > The only case where we should warn users
> > is i2c_rate > typical_rate, because that might lead to malfunctions.
>
> Can you explain why?
Because the speed is limited by the device capabilities. Using a slower
freq works, driving the SLC line faster than what's supported by I2C
slaves doesn't.
>
> >
> > >
> > > > just
> > > > like I'm not convinced having an I3C rate that's slower than the I2C
> > > > one is a problem (it's definitely a weird situation, but there's nothing
> > > > preventing that in the spec).
> > >
> > > You agree that there is no point for case where i3c rate < i2c rate yet
> > > you are not convinced.
> >
> > I didn't say that, there might be use cases where one wants to slow
> > down the I3C bus to be able to probe it or use a slower rate when
> > things do not work properly. It's rather unlikely to happen, but I
> > don't think it deserves a warning message when that's the case.
> >
> > > Do you thing that will be users for this case?
> > >
> > > Anyway, this isn't a high requirement for me. The all point of this patch
> > > is to introduce the limited bus configuration.
> >
> > And yet, you keep insisting (and ignoring my feedback) on that point :P.
>
> If you check the previous version you see that I'm trying to follow ????
> I will change the dev_warn() to dev_dbg() due the trace is indeed too
> much.
I have the feeling that you endlessly argue on details while the vast
majority of changes are okay, which means we both spend a lot of time
on things that are not super important.