[PATCH v2 15/20] drm/msm/dp: Flush VSC updates when leaving YUV420

[Dmitry Baryshkov]

On Fri, Oct 09, 2026 at 11:16:07AM +0800, Xilin Wu wrote:
> Peripheral flush is currently requested only for the new YUV420 mode.
> Returning to RGB also changes SDP state and must remove the old VSC
> packet rather than leaving its enable bits set.
> 
> Track whether either stream needs VSC and request peripheral flush for
> both enabling and removing it. Explicitly disable VSC for RGB, and write
> the packet payload before enabling transmission. Retain the existing
> hardware-specific SDP update mechanism.

Missing Fixes tag.

> 
> Assisted-by: LLM
> Signed-off-by: Xilin Wu <sophon at radxa.com>
> ---
>  drivers/gpu/drm/msm/dp/dp_display.c | 7 ++++++-
>  drivers/gpu/drm/msm/dp/dp_panel.c   | 6 ++++--
>  drivers/gpu/drm/msm/dp/dp_panel.h   | 1 +
>  3 files changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index 1f9595ff5fd9..486348113b8a 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -691,6 +691,8 @@ static int msm_dp_display_set_mode(struct msm_dp *msm_dp_display,
>  	else
>  		bpp = state->bpp;
>  
> +	msm_dp_panel->sdp_needs_flush = msm_dp_panel->msm_dp_mode.out_fmt_is_yuv_420 ||
> +		drm_mode_is_420_only(&msm_dp_panel->connector->display_info, adjusted_mode);

Does it need locking? Can we instead store if SDP is goign to be used in
the atomic state and then pass both old and new state here, letting the
bridge to determine if the SDP status is being changed on this modeset.

>  	msm_dp_panel_init_panel_info(msm_dp_panel, adjusted_mode, bpp ? bpp : 24);
>  
>  	/* populate wide_bus_support to different layers */

-- 
With best wishes
Dmitry