Re: [PATCH v2 4/4] drm/i915/3dlut: disable 3D LUT if unsupported

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

On 8/4/2026 3:19 AM, Michał Grzelak wrote:
> XE2LPD_DE_CAP_3DLUT_MASK is defined but never used.
> 
> Check DE_CAP with the mask whether 3D LUT is disabled for LNL+. Reset
> has_3dlut if that is the case.
> 
> Bspec: 71161
> Cc: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
> Cc: <stable@vger.kernel.org>
> Fixes: 6d181a288e64 ("drm/i915/xe2lpd: update the dsc feature capability")

For this one you can actually add the Fixes tag with 65db7a1f9cf7 
("drm/i915/color: Add 3D LUT to color pipeline"), because this would 
make sense for NVL+ platforms where the CAP bit is used.

As for stable branches, you would need all the patches that adds the 
infrastructure for has_3dlut to land together. Not sure what is the best 
way to do it.

Other than that, changes makes sense.

> Signed-off-by: Michał Grzelak <michal.grzelak@intel.com>
> ---
>   drivers/gpu/drm/i915/display/intel_display_device.c | 4 ++++
>   drivers/gpu/drm/i915/display/intel_display_regs.h   | 1 +
>   2 files changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_device.c b/drivers/gpu/drm/i915/display/intel_display_device.c
> index a2bea5ac59cf..d4e52e627b34 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_device.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_device.c
> @@ -1940,6 +1940,10 @@ static void __intel_display_device_info_runtime_init(struct intel_display *displ
>   	if (DISPLAY_VER(display) >= 20) {
>   		u32 cap = intel_de_read(display, XE2LPD_DE_CAP);
>   
> +		if (REG_FIELD_GET(XE2LPD_DE_CAP_3DLUT_MASK, cap) ==
> +		    XE2LPD_DE_CAP_3DLUT_REMOVED)
> +			display_runtime->has_3dlut = 0;
> +
>   		if (REG_FIELD_GET(XE2LPD_DE_CAP_DSC_MASK, cap) ==
>   		    XE2LPD_DE_CAP_DSC_REMOVED)
>   			display_runtime->has_dsc = 0;
> diff --git a/drivers/gpu/drm/i915/display/intel_display_regs.h b/drivers/gpu/drm/i915/display/intel_display_regs.h
> index 740331ead20a..78b9e6008828 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_regs.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_regs.h
> @@ -1773,6 +1773,7 @@
>   
>   #define XE2LPD_DE_CAP			_MMIO(0x41100)
>   #define   XE2LPD_DE_CAP_3DLUT_MASK	REG_GENMASK(31, 30)
> +#define   XE2LPD_DE_CAP_3DLUT_REMOVED	1
>   #define   XE2LPD_DE_CAP_DSC_MASK	REG_GENMASK(29, 28)
>   #define   XE2LPD_DE_CAP_DSC_REMOVED	1
>   #define   XE2LPD_DE_CAP_SCALER_MASK	REG_GENMASK(27, 26)