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SubjectRe: [PATCH 2/3] i3c: add mixed limited bus mode
Hi Vitor,

On Mon, 15 Apr 2019 20:46:42 +0200
Vitor Soares <vitor.soares@synopsys.com> wrote:

> The i3c bus spec define a bus configuration where the i2c devices

^defines I2C devices...

> doesn't have the 50ns filter yet they allow the SDR max speed.

^don't ^ a 50ns filter but support SCL running at SDR max
rate (12MHz).

>
> This patch introduce the limited bus mode so the users can use

^introduces ^ so that users

> a higher speed on presence of i2c devices index 1.

^in

>
> Signed-off-by: Vitor Soares <vitor.soares@synopsys.com>
> Cc: Boris Brezillon <bbrezillon@kernel.org>
> Cc: <linux-kernel@vger.kernel.org>
> ---
> drivers/i3c/master.c | 5 +++++
> include/linux/i3c/master.h | 5 +++++
> 2 files changed, 10 insertions(+)
>
> diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> index 1c4a86a..46d3774 100644
> --- a/drivers/i3c/master.c
> +++ b/drivers/i3c/master.c
> @@ -463,6 +463,7 @@ static int i3c_bus_init(struct i3c_bus *i3cbus)
> static const char * const i3c_bus_mode_strings[] = {
> [I3C_BUS_MODE_PURE] = "pure",
> [I3C_BUS_MODE_MIXED_FAST] = "mixed-fast",
> + [I3C_BUS_MODE_MIXED_LIMITED] = "mixed-limited",
> [I3C_BUS_MODE_MIXED_SLOW] = "mixed-slow",
> };
>
> @@ -575,6 +576,7 @@ int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode,
> i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> break;
> case I3C_BUS_MODE_MIXED_FAST:
> + case I3C_BUS_MODE_MIXED_LIMITED:
> if (!i3cbus->scl_rate.i3c)
> i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
> if (!i3cbus->scl_rate.i2c)
> @@ -2481,6 +2483,9 @@ int i3c_master_register(struct i3c_master_controller *master,
> mode = I3C_BUS_MODE_MIXED_FAST;
> break;
> case I3C_LVR_I2C_INDEX(1):
> + if (mode < I3C_BUS_MODE_MIXED_LIMITED)
> + mode = I3C_BUS_MODE_MIXED_LIMITED;
> + break;
> case I3C_LVR_I2C_INDEX(2):
> if (mode < I3C_BUS_MODE_MIXED_SLOW)
> mode = I3C_BUS_MODE_MIXED_SLOW;
> diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h
> index 44fb3cf..740235e 100644
> --- a/include/linux/i3c/master.h
> +++ b/include/linux/i3c/master.h
> @@ -250,12 +250,17 @@ struct i3c_device {
> * the bus. The only impact in this mode is that the
> * high SCL pulse has to stay below 50ns to trick I2C
> * devices when transmitting I3C frames
> + * @I3C_BUS_MODE_MIXED_LIMITED: I2C devices without 50ns spike filter are
> + * present on the bus. However they allows
> + * compliance up to the maximum SDR SCL clock
> + * frequency.

However they support
SCL clock running at maximum SDR rate
(12.5MHz).

> * @I3C_BUS_MODE_MIXED_SLOW: I2C devices without 50ns spike filter are present
> * on the bus
> */
> enum i3c_bus_mode {
> I3C_BUS_MODE_PURE,
> I3C_BUS_MODE_MIXED_FAST,
> + I3C_BUS_MODE_MIXED_LIMITED,
> I3C_BUS_MODE_MIXED_SLOW,
> };
>

The code itself looks good.

Thanks,

Boris

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