Re: [PATCH v2 08/32] drm/i915/xe3p_lpd: Extend FBC support to UINT16 formats

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Oct 21, 2025 at 09:28:33PM -0300, Gustavo Sousa wrote:
> From: Sai Teja Pottumuttu <sai.teja.pottumuttu@intel.com>
> 
> Starting Xe3p_LPD, FBC is supported on UINT16 formats as well. Also
> UINT16 being a 64bpp format, will use cpp of 8 for cfb stride and thus
> size calculations.
> 
> Cc: Shekhar Chauhan <shekhar.chauhan@intel.com>
> BSpec: 68881, 68904, 69560
> Signed-off-by: Sai Teja Pottumuttu <sai.teja.pottumuttu@intel.com>
> Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_fbc.c | 42 ++++++++++++++++++++++++++++----
>  1 file changed, 37 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
> index 10ef3136dadc..af3585aeefd3 100644
> --- a/drivers/gpu/drm/i915/display/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/display/intel_fbc.c
> @@ -141,15 +141,25 @@ static unsigned int intel_fbc_plane_stride(const struct intel_plane_state *plane
>  	return stride;
>  }
>  
> -static unsigned int intel_fbc_cfb_cpp(void)
> +static unsigned int intel_fbc_cfb_cpp(const struct intel_plane_state *plane_state)
>  {
> -	return 4; /* FBC always 4 bytes per pixel */
> +	const struct drm_framebuffer *fb = plane_state->hw.fb;
> +
> +	switch (fb->format->format) {
> +	case DRM_FORMAT_XRGB16161616:
> +	case DRM_FORMAT_XBGR16161616:
> +	case DRM_FORMAT_ARGB16161616:
> +	case DRM_FORMAT_ABGR16161616:
> +		return 8;
> +	default:
> +		return 4;
> +	}

return max(cpp, 4);

>  }
>  
>  /* plane stride based cfb stride in bytes, assuming 1:1 compression limit */
>  static unsigned int intel_fbc_plane_cfb_stride(const struct intel_plane_state *plane_state)
>  {
> -	unsigned int cpp = intel_fbc_cfb_cpp();
> +	unsigned int cpp = intel_fbc_cfb_cpp(plane_state);
>  
>  	return intel_fbc_plane_stride(plane_state) * cpp;
>  }
> @@ -203,7 +213,7 @@ static unsigned int intel_fbc_cfb_stride(const struct intel_plane_state *plane_s
>  	struct intel_display *display = to_intel_display(plane_state->uapi.plane->dev);
>  	unsigned int stride = intel_fbc_plane_cfb_stride(plane_state);
>  	unsigned int width = drm_rect_width(&plane_state->uapi.src) >> 16;
> -	unsigned int cpp = intel_fbc_cfb_cpp();
> +	unsigned int cpp = intel_fbc_cfb_cpp(plane_state);
>  
>  	return _intel_fbc_cfb_stride(display, cpp, width, stride);
>  }
> @@ -1081,11 +1091,33 @@ static bool lnl_fbc_pixel_format_is_valid(const struct intel_plane_state *plane_
>  	}
>  }
>  
> +static bool xe3p_lpd_fbc_pixel_format_is_valid(const struct intel_plane_state *plane_state)
> +{
> +	const struct drm_framebuffer *fb = plane_state->hw.fb;
> +
> +	switch (fb->format->format) {
> +	case DRM_FORMAT_XRGB8888:
> +	case DRM_FORMAT_XBGR8888:
> +	case DRM_FORMAT_ARGB8888:
> +	case DRM_FORMAT_ABGR8888:
> +	case DRM_FORMAT_RGB565:
> +	case DRM_FORMAT_XRGB16161616:
> +	case DRM_FORMAT_XBGR16161616:
> +	case DRM_FORMAT_ARGB16161616:
> +	case DRM_FORMAT_ABGR16161616:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
>  static bool pixel_format_is_valid(const struct intel_plane_state *plane_state)
>  {
>  	struct intel_display *display = to_intel_display(plane_state->uapi.plane->dev);
>  
> -	if (DISPLAY_VER(display) >= 20)
> +	if (DISPLAY_VER(display) >= 35)
> +		return xe3p_lpd_fbc_pixel_format_is_valid(plane_state);
> +	else if (DISPLAY_VER(display) >= 20)
>  		return lnl_fbc_pixel_format_is_valid(plane_state);
>  	else if (DISPLAY_VER(display) >= 5 || display->platform.g4x)
>  		return g4x_fbc_pixel_format_is_valid(plane_state);
> 
> -- 
> 2.51.0

-- 
Ville Syrjälä
Intel