Re: [PATCH v2 01/13] drm/i915: Give up on DSB/flip queue if we fail to allocate the color DSB buffer

["Borah, Chaitanya Kumar" <chaitanya.kumar.borah@intel.com>]

On 9/9/2026 9:47 PM, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> We don't have a codepath that does the color LUT update via
> MMIO while writing the double buffered registers via DSB/flip queue.
> So if we fail to allocate the DSB buffer for the LUT update we have
> to fall back to a full MMIO based update. Make it so.
> 
> If we hit this with the current code then the entire LUT update
> is simply skipped. After the fix the entire update, including
> the LUT, will happen.
>

Does it need a fixes tag?

Either way, LGTM.

Reviewed-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>


> v2: Keep the use_dsb check in intel_crtc_needs_vblank_work()
>      for the case when we need a color update but we have no
>      LUTs, and thus we can end up doing the update via the DSB
>      with intel_color_uses_dsb()==false
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>   drivers/gpu/drm/i915/display/intel_color.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_color.c b/drivers/gpu/drm/i915/display/intel_color.c
> index 87ced9f6ff40..26e92221fa19 100644
> --- a/drivers/gpu/drm/i915/display/intel_color.c
> +++ b/drivers/gpu/drm/i915/display/intel_color.c
> @@ -2028,8 +2028,11 @@ void intel_color_prepare_commit(struct intel_atomic_state *state,
>   	else
>   		crtc_state->dsb_color = intel_dsb_prepare(state, crtc, INTEL_DSB_1, 1024);
>   
> -	if (!intel_color_uses_dsb(crtc_state))
> +	if (!intel_color_uses_dsb(crtc_state)) {
> +		crtc_state->use_flipq = false;
> +		crtc_state->use_dsb = false;
>   		return;
> +	}
>   
>   	display->color.funcs->load_luts(crtc_state);
>