Re: [PATCH] i2c: qcom-cci: skip core clock rates the clock cannot provide

[Loic Poulain]

On Fri, Oct 9, 2026 at 1:07 AM Oleg Keri <okerixx@xxxxxxxxx> wrote:
>
> cci_get_required_rate() picks the lowest rate that has timings for every
> active master, but never checks that the CCI clock can run at it. On
> glymur, sm8750 and kaanapali the CCI clock table has no 19.2 MHz entry,
> so the request rounds up to 30 MHz or 37.5 MHz, the timing lookup for
> the running rate fails and the controller does not probe:
>
>   i2c-qcom-cci ac16000.cci: CCI clock is not at expected 19200000 Hz
>   i2c-qcom-cci ac16000.cci: no timing for mode 1 at CCI clock 30000000 Hz
>   i2c-qcom-cci ac16000.cci: probe with driver i2c-qcom-cci failed with error -95

sm8750 and kaanapali have a single 37.5Mhz frequency point which
should not cause a probe failure.

>
> Only consider rates clk_round_rate() can deliver exactly. Glymur then
> runs its CCI at 37.5 MHz, which has timings for every mode.
>
> Fixes: fa1eb3af12fa ("i2c: qcom-cci: Enforce the required CCI clock rate")

Reviewed-by: Loic Poulain <loic.poulain@xxxxxxxxxxxxxxxx>


> Signed-off-by: Oleg Keri <okerixx@xxxxxxxxx>
> ---
>  drivers/i2c/busses/i2c-qcom-cci.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-qcom-cci.c b/drivers/i2c/busses/i2c-qcom-cci.c
> index 6d8be7b8b79d..289368c00fe4 100644
> --- a/drivers/i2c/busses/i2c-qcom-cci.c
> +++ b/drivers/i2c/busses/i2c-qcom-cci.c
> @@ -586,6 +586,9 @@ static int cci_get_required_rate(struct cci *cci, unsigned long *rate)
>         for (int ri = 0; ri < NUM_CCI_CLK_RATES; ri++) {
>                 bool supported = true;
>
> +               if (clk_round_rate(cci->cci_clk, cci_clk_rates[ri]) != cci_clk_rates[ri])
> +                       continue;
> +
>                 for (int i = 0; i < cci->data->num_masters; i++) {
>                         int mode = cci->master[i].mode;
>
> --
> 2.55.0
>