Re: [PATCH] drm/i915/scaler: Update Pipe src size check for DISPLAY_VER >= 12

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

On Mon, Feb 19, 2024 at 11:22:55AM +0530, Ankit Nautiyal wrote:
> For Earlier platforms, the Pipe source size is 12-bits so
> max pipe source width and height is 4096. For newer platforms it is
> 13-bits so theoretically max height is 8192, but maximum width
> supported on a single pipe is 5120, beyond which we need to use
> bigjoiner.
> 
> Currently we are using max scaler source size to make sure that the
> pipe source size is programmed within limits, before using scaler.
> This creates a problem, for MTL where scaler source size is 4096, but
> max pipe source width can be 5120.
> 
> Update the check to use the aforementioned limits.
> 
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> ---
>  drivers/gpu/drm/i915/display/skl_scaler.c | 19 +++++++++++++++----
>  1 file changed, 15 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/skl_scaler.c b/drivers/gpu/drm/i915/display/skl_scaler.c
> index 8a934bada624..36342142efaa 100644
> --- a/drivers/gpu/drm/i915/display/skl_scaler.c
> +++ b/drivers/gpu/drm/i915/display/skl_scaler.c
> @@ -115,6 +115,7 @@ skl_update_scaler(struct intel_crtc_state *crtc_state, bool force_detach,
>  	int pipe_src_h = drm_rect_height(&crtc_state->pipe_src);
>  	int min_src_w, min_src_h, min_dst_w, min_dst_h;
>  	int max_src_w, max_src_h, max_dst_w, max_dst_h;
> +	int max_pipe_src_w, max_pipe_src_h;
>  
>  	/*
>  	 * Src coordinates are already rotated by 270 degrees for
> @@ -212,11 +213,21 @@ skl_update_scaler(struct intel_crtc_state *crtc_state, bool force_detach,
>  	/*
>  	 * The pipe scaler does not use all the bits of PIPESRC, at least
>  	 * on the earlier platforms. So even when we're scaling a plane
> -	 * the *pipe* source size must not be too large. For simplicity
> -	 * we assume the limits match the scaler source size limits. Might
> -	 * not be 100% accurate on all platforms, but good enough for now.
> +	 * the *pipe* source size must not be too large.
> +	 *
> +	 * For Earlier platforms, the Pipe source size is 12-bits so
> +	 * max pipe src width and height is 4096. For newer platforms it is 13-bits.
> +	 * Theoretically maximum pipe src height supported on a single pipe is 8192,
> +	 * but maximum pipe src width supported on a single pipe is 5120.
>  	 */
> -	if (pipe_src_w > max_src_w || pipe_src_h > max_src_h) {
> +	if (DISPLAY_VER(dev_priv) < 12) {
> +		max_pipe_src_w = 4096;
> +		max_pipe_src_h = 4096;

That doesn't seem right.

Hmm. We should probably we able to just switch this to check 
against the max dst size instead of the max src size.

> +	} else {
> +		max_pipe_src_w = 5120;
> +		max_pipe_src_h = 8192;
> +	}
> +	if (pipe_src_w > max_pipe_src_w || pipe_src_h > max_pipe_src_h) {
>  		drm_dbg_kms(&dev_priv->drm,
>  			    "scaler_user index %u.%u: pipe src size %ux%u "
>  			    "is out of scaler range\n",
> -- 
> 2.40.1

-- 
Ville Syrjälä
Intel