Re: [PATCH] drm/msm/dsi: remove bpc > 8 entries from allow list

[Eugene Lepshy <fekz115@gmail.com>]

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Hi,

I have a concern regarding this patch. The Nothing Phone (1) (sm7325-nothing-spacewar), which is already supported in mainline, utilizes a panel with bpc=10 and bpp=8 (DSC) [1].

Currently, this configuration works properly. While I have encountered minor graphical artifacts during brightness changes, the display output is otherwise reliable across all supported refresh rates (60/90/120 Hz).

Since this panel is already upstreamed, this patch might cause regressions.

[1] https://github.com/NothingOSS/android_kernel_devicetree_nothing_sm7325/blob/6f027f0440e3dce8a674d9cbd2f6ad944120e209/msm-extra/display-devicetree/display/dsi-panel-rm692e5-visionox-fhd-plus-120hz-cmd.dtsi#L483-L484

Best regards,
Eugene Lepshy

On March 6, 2026 9:47:23 PM GMT+03:00, Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com> wrote:
>On Fri, Mar 06, 2026 at 05:25:00PM +0800, Pengyu Luo wrote:
>> In upstream the msm, for bpc greater than 8 are not supported yet,
>> although the hardware block supports this. Remove them until we
>> support them.
>> 
>> Fixes: b0e71c2637d1 ("drm/msm/dsi: Allow values of 10 and 12 for bits per component")
>> Signed-off-by: Pengyu Luo <mitltlatltl@gmail.com>
>
>I hope Marijn, Danila or Eugeny can comment. The patch series with this
>patchset added 10 bpc panel and used it for one of the phones.
>
>> ---
>>  drivers/gpu/drm/msm/dsi/dsi_host.c | 7 ++-----
>>  1 file changed, 2 insertions(+), 5 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
>> index e8e83ee61e..b60b26ddb0 100644
>> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
>> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
>> @@ -1824,12 +1824,9 @@ static int dsi_populate_dsc_params(struct msm_dsi_host *msm_host, struct drm_dsc
>>  
>>  	switch (dsc->bits_per_component) {
>>  	case 8:
>> -	case 10:
>> -	case 12:
>>  		/*
>> -		 * Only 8, 10, and 12 bpc are supported for DSC 1.1 block.
>> -		 * If additional bpc values need to be supported, update
>> -		 * this quard with the appropriate DSC version verification.
>> +		 * In the upstream msm, only 8 bpc is supported for DSC 1.1/1.2
>> +		 * block.
>>  		 */
>>  		break;
>>  	default:
>> -- 
>> 2.53.0
>> 
>
>-- 
>With best wishes
>Dmitry

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