Re: [PATCH v4] drm/i915/skl: Implement the skl version of MMIO flips

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

On Thu, Nov 20, 2014 at 01:48:35PM +0000, Damien Lespiau wrote:
> Because the plane registers are different in Skylake we need to adapt
> the MMIO code as well.
> 
> v2: Don't introduce yet another vfunc when the direction is do
> consolidate the plane updates to use the same code path (Daniel)
> 
> v3:
>   - Use enum pipe instead of int (Ville)
>   - Also update PLANE_STRIDE when the tiling has changed (Ville)
>   - Put intel_mark_page_flip_active() in the shared code (Damien)
> 
> v4:
>   - Remove unused variable
> 
> Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>

Looks OK. I'm not super happy about looking at plane->fb here, but the
code already did that. And it should work as long as we don't allow
queuing multiple flips and the plane->fb gets update after the pending
flip wait. But as the comment now says this is a temporary solution and
should hopefully get sorted out in the end.

The patch seems whitespace damaged though (lots of spaces where tabs
should be). With that fixed:
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/intel_display.c | 64 ++++++++++++++++++++++++++++++++----
>  1 file changed, 57 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index c0af4c6..9a52d7e 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -9436,22 +9436,50 @@ static bool use_mmio_flip(struct intel_engine_cs *ring,
>  		return ring != obj->ring;
>  }
>  
> -static void intel_do_mmio_flip(struct intel_crtc *intel_crtc)
> +static void skl_do_mmio_flip(struct intel_crtc *intel_crtc)
> +{
> +       struct drm_device *dev = intel_crtc->base.dev;
> +       struct drm_i915_private *dev_priv = dev->dev_private;
> +       struct drm_framebuffer *fb = intel_crtc->base.primary->fb;
> +       struct intel_framebuffer *intel_fb = to_intel_framebuffer(fb);
> +       struct drm_i915_gem_object *obj = intel_fb->obj;
> +       const enum pipe pipe = intel_crtc->pipe;
> +       u32 ctl, stride;
> +
> +       ctl = I915_READ(PLANE_CTL(pipe, 0));
> +       ctl &= ~PLANE_CTL_TILED_MASK;
> +       if (obj->tiling_mode == I915_TILING_X)
> +               ctl |= PLANE_CTL_TILED_X;
> +
> +	/*
> +	 * The stride is either expressed as a multiple of 64 bytes chunks for
> +	 * linear buffers or in number of tiles for tiled buffers.
> +	 */
> +       stride = fb->pitches[0] >> 6;
> +       if (obj->tiling_mode == I915_TILING_X)
> +		stride = fb->pitches[0] >> 9; /* X tiles are 512 bytes wide */
> +
> +	/*
> +	 * Both PLANE_CTL and PLANE_STRIDE are not updated on vblank but on
> +	 * PLANE_SURF updates, the update is then guaranteed to be atomic.
> +	 */
> +       I915_WRITE(PLANE_CTL(pipe, 0), ctl);
> +       I915_WRITE(PLANE_STRIDE(pipe, 0), stride);
> +
> +       I915_WRITE(PLANE_SURF(pipe, 0), intel_crtc->unpin_work->gtt_offset);
> +       POSTING_READ(PLANE_SURF(pipe, 0));
> +}
> +
> +static void ilk_do_mmio_flip(struct intel_crtc *intel_crtc)
>  {
>  	struct drm_device *dev = intel_crtc->base.dev;
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	struct intel_framebuffer *intel_fb =
>  		to_intel_framebuffer(intel_crtc->base.primary->fb);
>  	struct drm_i915_gem_object *obj = intel_fb->obj;
> -	bool atomic_update;
> -	u32 start_vbl_count;
>  	u32 dspcntr;
>  	u32 reg;
>  
> -	intel_mark_page_flip_active(intel_crtc);
> -
> -	atomic_update = intel_pipe_update_start(intel_crtc, &start_vbl_count);
> -
>  	reg = DSPCNTR(intel_crtc->plane);
>  	dspcntr = I915_READ(reg);
>  
> @@ -9466,6 +9494,28 @@ static void intel_do_mmio_flip(struct intel_crtc *intel_crtc)
>  		   intel_crtc->unpin_work->gtt_offset);
>  	POSTING_READ(DSPSURF(intel_crtc->plane));
>  
> +}
> +
> +/*
> + * XXX: This is the temporary way to update the plane registers until we get
> + * around to using the usual plane update functions for MMIO flips
> + */
> +static void intel_do_mmio_flip(struct intel_crtc *intel_crtc)
> +{
> +	struct drm_device *dev = intel_crtc->base.dev;
> +	bool atomic_update;
> +	u32 start_vbl_count;
> +
> +	intel_mark_page_flip_active(intel_crtc);
> +
> +	atomic_update = intel_pipe_update_start(intel_crtc, &start_vbl_count);
> +
> +	if (INTEL_INFO(dev)->gen >= 9)
> +		skl_do_mmio_flip(intel_crtc);
> +	else
> +		/* use_mmio_flip() retricts MMIO flips to ilk+ */
> +		ilk_do_mmio_flip(intel_crtc);
> +
>  	if (atomic_update)
>  		intel_pipe_update_end(intel_crtc, start_vbl_count);
>  }
> -- 
> 1.8.3.1
> 
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-- 
Ville Syrjälä
Intel OTC
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