[Intel-gfx] [PATCH 1/2] drm/i915/skl: Don't expose the top most plane on gen9 display

[Konduru, Chandra]

> -----Original Message-----
> From: Intel-gfx [mailto:intel-gfx-bounces at lists.freedesktop.org] On Behalf Of
> Damien Lespiau
> Sent: Thursday, July 16, 2015 9:08 AM
> To: intel-gfx at lists.freedesktop.org
> Subject: [Intel-gfx] [PATCH 1/2] drm/i915/skl: Don't expose the top most plane
> on gen9 display
> 
> on SKL/BXT, the top most plane hardware is shared between the legacy
> cursor registers and an actual plane. Daniel and Ville don't want to
> expose 2 DRM planes and would rather expose a CURSOR plane that has all
> the usual plane properties, and that's a blocker for lifting the
> prelimary_hw_support flag.
> 
> Unfortunately noone has had the time to finish this yet, but lifting the
> prelimary_hw_support flag is long overdue. As an intermediate solution
> we can merely not expose the top most plane
> 
> Cc: Imre Deak <imre.deak at intel.com>
> Signed-off-by: Damien Lespiau <damien.lespiau at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_dma.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_dma.c
> b/drivers/gpu/drm/i915/i915_dma.c
> index 91925cb..96564cd 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -726,11 +726,19 @@ static void intel_device_info_runtime_init(struct
> drm_device *dev)
> 
>  	info = (struct intel_device_info *)&dev_priv->info;
> 
> +	/*
> +	 * Skylake and Broxton currently don't expose the topmost plane as its
> +	 * use is exclusive with the legacy cursor and we only want to expose
> +	 * one of those, not both. Until we can safely expose the topmost plane
> +	 * as a DRM_PLANE_TYPE_CURSOR with all the features
> exposed/supported,
> +	 * we don't expose the topmost plane at all to prevent ABI breakage
> +	 * down the line.
> +	 */
>  	if (IS_BROXTON(dev)) {
> -		info->num_sprites[PIPE_A] = 3;
> -		info->num_sprites[PIPE_B] = 3;
> -		info->num_sprites[PIPE_C] = 2;
> -	} else if (IS_VALLEYVIEW(dev) || INTEL_INFO(dev)->gen == 9)
> +		info->num_sprites[PIPE_A] = 2;
> +		info->num_sprites[PIPE_B] = 2;
> +		info->num_sprites[PIPE_C] = 1;
> +	} else if (IS_VALLEYVIEW(dev))
>  		for_each_pipe(dev_priv, pipe)
>  			info->num_sprites[pipe] = 2;

For SKL, by default you can keep as 2 planes + 1 cursor, but let 
userland change to 3 planes + no cursor. This is a one-time 
request only and not ping ponging between 2+1 and 3+0.
For Android, this gives flexibility to use 3 planes where 
cursor isn't a dominant case. 

Similarly, for BXT, allow 4+0 and keep 3+1 as default for 
legacy userlands.
 
>  	else
> --
> 2.1.0
> 
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