Re: [PATCH v3 13/13] drm/panel-simple: Fix powertip,ph800480t013-idf02 timings

[Neil Armstrong <neil.armstrong@linaro.org>]

On 5/13/26 15:10, Tomi Valkeinen wrote:
> The powertip,ph800480t013-idf02 panel was added to panel-simple, and
> with the tc358762 driver, enabled the use of RaspberryPi 7" DSI display.
> 
> I have been testing the RaspberryPi 7" DSI display module with TI's
> BeagleY-AI, and I can't get a good image with the current panel timings.
> 
> It's been quite difficult to figure out exactly what are the issues.
> Possibly RPi DSI TX and TI DSI TX have their own quirks which affect
> this also. However, now that the tc358762 driver has been fixed wrt. the
> signal timings it sends, this patch makes the panel work fine on
> BeagleY-AI.
> 
> Fix the timings according to the datasheet:
> 
> - hsw + hbp must equal to 46. This was correct in the timings, but the
>    hsw was very tight, and at least Cadence DSI has trouble with such
>    short hsync. Increase hsw to the middle of the hsw range from the
>    datasheet, and decrease hbp accordingly.
> - vsw + vbp must equal to 23. This was 24, resulting in slight shift in
>    the image.
> - The upstream timings seemed to aim for 50 fps, but this is a normal 60
>    fps panel, so adjust the timings to get 60 fps. As there's no strict
>    rule what numbers to pick here, I used the "typical" values from panel
>    datasheet for pclk, hfp and vfp. However, vfp of 23 instead of the
>    datasheet's 22 give us a closer match to 60 fps, so I used that.
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> ---
>   drivers/gpu/drm/panel/panel-simple.c | 14 +++++++-------
>   1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> index 91ab280869ba..16aeafd2b02e 100644
> --- a/drivers/gpu/drm/panel/panel-simple.c
> +++ b/drivers/gpu/drm/panel/panel-simple.c
> @@ -4041,15 +4041,15 @@ static const struct panel_desc powertip_ph128800t006_zhc01 = {
>   };
>   
>   static const struct drm_display_mode powertip_ph800480t013_idf02_mode = {
> -	.clock = 24750,
> +	.clock = 33333,
>   	.hdisplay = 800,
> -	.hsync_start = 800 + 54,
> -	.hsync_end = 800 + 54 + 2,
> -	.htotal = 800 + 54 + 2 + 44,
> +	.hsync_start = 800 + 210,
> +	.hsync_end = 800 + 210 + 20,
> +	.htotal = 800 + 210 + 20 + 26,
>   	.vdisplay = 480,
> -	.vsync_start = 480 + 49,
> -	.vsync_end = 480 + 49 + 2,
> -	.vtotal = 480 + 49 + 2 + 22,
> +	.vsync_start = 480 + 23,
> +	.vsync_end = 480 + 23 + 2,
> +	.vtotal = 480 + 23 + 2 + 21,
>   	.flags = DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_NHSYNC,
>   };
>   
> 

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>

Thanks,
Neil