Re: [PATCH 2/2] drm/i915/fbc: Allow on unfenced surfaces, for recent gen

[Joonas Lahtinen <joonas.lahtinen@linux.intel.com>]

On to, 2016-08-18 at 09:21 +0100, Chris Wilson wrote:
> Only fbc1 is tied to using a fence. Later iterations of fbc are more
> flexible and allow operation on unfenced frontbuffers.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Daniel Vetter <daniel.vetter@intel.com>
> Cc: "Zanoni, Paulo R" <paulo.r.zanoni@intel.com>

I could only find that unfenced compressed framebuffer does not work on
Gen4 but will work Gen6.

So somebody should test with Gen5. Maybe we should document this as a
comment?

Code itself makes sense;

Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

Regards, Joonas

> ---
>  drivers/gpu/drm/i915/intel_fbc.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
> index 57e1ca624d73..9534f90c6551 100644
> --- a/drivers/gpu/drm/i915/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/intel_fbc.c
> @@ -789,8 +789,10 @@ static bool intel_fbc_can_activate(struct intel_crtc *crtc)
>  	 */
>  	if (cache->fb.tiling_mode != I915_TILING_X ||
>  	    cache->fb.fence_reg == I915_FENCE_REG_NONE) {
> -		fbc->no_fbc_reason = "framebuffer not tiled or fenced";
> -		return false;
> +		if (INTEL_GEN(dev_priv) < 5) {
> +			fbc->no_fbc_reason = "framebuffer not tiled or fenced";
> +			return false;
> +		}
>  	}
>  	if (INTEL_INFO(dev_priv)->gen <= 4 && !IS_G4X(dev_priv) &&
>  	    cache->plane.rotation != DRM_ROTATE_0) {
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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