Re: [PATCH] i2c: qcom-geni: restore tSCL with 32MHz I2C fast-mode

[Mukesh Savaliya <mukesh.savaliya@oss.qualcomm.com>]

Thanks Daniel !

On 9/29/2026 9:44 AM, Daniel J Blueman wrote:
> Commit cb97bf3d4f91 ("i2c: qcom-geni: Fix hardcoded clock index in
> SE_GENI_CLK_SEL") allowed GENI to use 32MHz clock. This changed I2C
> timing, making the Yoga Slim 7x keyboard (ITE 048D:8987) unusable
> on all boots, and touchpad unusable on some boots, resulting in:
> 
>    i2c_hid_of 1-003a: unexpected HID descriptor bcdVersion (0x0000)
>    i2c_hid_of 1-002c: failed to fetch HID descriptor: -110
> 
> With this change, t_high_cnt 3 and clk_div 4 gave a tSCL of 375ns
> versus the previous default of 521ns, however the I2C spec has a
> minimum tSCL of 600ns.
> 
> Restore tSCL to the spec with t_high_cnt 5 giving a 625ns tSCL,
> verified on Lenovo Yoga Slim 7x X1E-80100.
> 

There might be a final count which i should get and update back.
Since this fix is working though not suggested per hardware guidance, 
should we consider as temporary fix and move ahead to prevent failing 
usecase ?

Any thought @andi ?

> Fixes: 506bb2ab0075 ("i2c: qcom-geni: Support systems with 32MHz serial engine clock")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Daniel J Blueman <daniel@quora.org>
> ---
>   drivers/i2c/busses/i2c-qcom-geni.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
> index 6a39e21d5ed4..1336a09ca183 100644
> --- a/drivers/i2c/busses/i2c-qcom-geni.c
> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
> @@ -193,7 +193,7 @@ static const struct geni_i2c_clk_fld geni_i2c_clk_map_19p2mhz[] = {
>   /* source_clock = 32 MHz */
>   static const struct geni_i2c_clk_fld geni_i2c_clk_map_32mhz[] = {
>   	{ I2C_MAX_STANDARD_MODE_FREQ, 12, 9, 10, 26 },
> -	{ I2C_MAX_FAST_MODE_FREQ, 4, 3, 9, 19 },
> +	{ I2C_MAX_FAST_MODE_FREQ, 4, 5, 9, 19 },

Exact change to come from hardware experts, till that i am hoping this 
revert should be fine.

>   	{ I2C_MAX_FAST_MODE_PLUS_FREQ, 2, 3, 5, 15 },
>   	{}
>   };