[PATCH v4] i2c: npcm: Add clock toggle recovery

[Mohammed Elbadry]

Thank you, Mukesh. Updated patch uploaded.

Mo

On Fri, Mar 28, 2025 at 12:33 PM <mohammed.0.elbadry at gmail.com> wrote:

> From: Tali Perry <tali.perry1 at gmail.com>
>
> During init of the bus, the module checks that the bus is idle.
> If one of the lines are stuck try to recover them first before failing.
> Sometimes SDA and SCL are low if improper reset occurs (e.g., reboot).
>
> Signed-off-by: Tali Perry <tali.perry1 at gmail.com>
> Signed-off-by: Mohammed Elbadry <mohammed.0.elbadry at gmail.com>
> ---
>  drivers/i2c/busses/i2c-npcm7xx.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-npcm7xx.c
> b/drivers/i2c/busses/i2c-npcm7xx.c
> index 2fe68615942e..caf9aa1e6319 100644
> --- a/drivers/i2c/busses/i2c-npcm7xx.c
> +++ b/drivers/i2c/busses/i2c-npcm7xx.c
> @@ -1967,10 +1967,14 @@ static int npcm_i2c_init_module(struct npcm_i2c
> *bus, enum i2c_mode mode,
>
>         /* Check HW is OK: SDA and SCL should be high at this point. */
>         if ((npcm_i2c_get_SDA(&bus->adap) == 0) ||
> (npcm_i2c_get_SCL(&bus->adap) == 0)) {
> -               dev_err(bus->dev, "I2C%d init fail: lines are low\n",
> bus->num);
> -               dev_err(bus->dev, "SDA=%d SCL=%d\n",
> npcm_i2c_get_SDA(&bus->adap),
> -                       npcm_i2c_get_SCL(&bus->adap));
> -               return -ENXIO;
> +               dev_warn(bus->dev, " I2C%d SDA=%d SCL=%d, attempting to
> recover\n", bus->num,
> +                                npcm_i2c_get_SDA(&bus->adap),
> npcm_i2c_get_SCL(&bus->adap));
> +               if (npcm_i2c_recovery_tgclk(&bus->adap)) {
> +                       dev_err(bus->dev, "I2C%d init fail: SDA=%d
> SCL=%d\n",
> +                               bus->num, npcm_i2c_get_SDA(&bus->adap),
> +                               npcm_i2c_get_SCL(&bus->adap));
> +                       return -ENXIO;
> +               }
>         }
>
>         npcm_i2c_int_enable(bus, true);
> --
> 2.49.0.472.ge94155a9ec-goog
>
>
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