linux-kernel - Re: [ 04/69] drm/i915: fix up ivb plane 3 pageflips

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Date:	Mon, 18 Jun 2012 18:55:56 -0300
From:	Herton Ronaldo Krzesinski <herton.krzesinski@...onical.com>
To:	Ben Hutchings <ben@...adent.org.uk>
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Daniel Vetter <daniel.vetter@...ll.ch>,
	Chris Wilson <chris@...is-wilson.co.uk>,
	Eugeni Dodonov <eugeni.dodonov@...el.com>
Subject: Re: [ 04/69] drm/i915: fix up ivb plane 3 pageflips

On Sun, Jun 17, 2012 at 06:59:45PM +0100, Ben Hutchings wrote:
> 3.2-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Daniel Vetter <daniel.vetter@...ll.ch>
> 
> commit cb05d8dedefa3066bf5d74ef88c6ca6cf4bd1c87 upstream.
> 
> Or at least plug another gapping hole. Apparrently hw desingers only
> moved the bit field, but did not bother ot re-enumerate the planes
> when adding support for a 3rd pipe.
> 
> Discovered by i-g-t/flip_test.
> 
> This may or may not fix the reference bugzilla, because that one
> smells like we have still larger fish to fry.
> 
> v2: Fixup the impossible case to catch programming errors, noticed by
> Chris Wilson.
> 
> References: https://bugs.freedesktop.org/show_bug.cgi?id=50069
> Acked-by: Chris Wilson <chris@...is-wilson.co.uk>
> Tested-by: Eugeni Dodonov <eugeni.dodonov@...el.com>
> Eugeni Dodonov <eugeni.dodonov@...el.com>
> Signed-Off-by: Daniel Vetter <daniel.vetter@...ll.ch>
> [bwh: Backported to 3.2: adjust context]
> Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
> ---
>  drivers/gpu/drm/i915/i915_reg.h      |    8 ++++++++
>  drivers/gpu/drm/i915/intel_display.c |   19 ++++++++++++++++++-
>  2 files changed, 26 insertions(+), 1 deletion(-)
> 
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -164,6 +164,14 @@
>  #define MI_DISPLAY_FLIP		MI_INSTR(0x14, 2)
>  #define MI_DISPLAY_FLIP_I915	MI_INSTR(0x14, 1)
>  #define   MI_DISPLAY_FLIP_PLANE(n) ((n) << 20)
> +/* IVB has funny definitions for which plane to flip. */
> +#define   MI_DISPLAY_FLIP_IVB_PLANE_A  (0 << 19)
> +#define   MI_DISPLAY_FLIP_IVB_PLANE_B  (1 << 19)
> +#define   MI_DISPLAY_FLIP_IVB_SPRITE_A (2 << 19)
> +#define   MI_DISPLAY_FLIP_IVB_SPRITE_B (3 << 19)
> +#define   MI_DISPLAY_FLIP_IVB_PLANE_C  (4 << 19)
> +#define   MI_DISPLAY_FLIP_IVB_SPRITE_C (5 << 19)
> +
>  #define MI_SET_CONTEXT		MI_INSTR(0x18, 0)
>  #define   MI_MM_SPACE_GTT		(1<<8)
>  #define   MI_MM_SPACE_PHYSICAL		(0<<8)
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -7176,17 +7176,34 @@
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
>  	struct intel_ring_buffer *ring = &dev_priv->ring[BCS];
> +	uint32_t plane_bit = 0;
>  	int ret;
>  
>  	ret = intel_pin_and_fence_fb_obj(dev, obj, ring);
>  	if (ret)
>  		goto err;
>  
> +	switch(intel_crtc->plane) {
> +	case PLANE_A:
> +		plane_bit = MI_DISPLAY_FLIP_IVB_PLANE_A;
> +		break;
> +	case PLANE_B:
> +		plane_bit = MI_DISPLAY_FLIP_IVB_PLANE_B;
> +		break;
> +	case PLANE_C:
> +		plane_bit = MI_DISPLAY_FLIP_IVB_PLANE_C;
> +		break;
> +	default:
> +		WARN_ONCE(1, "unknown plane in flip command\n");
> +		ret = -ENODEV;
> +		goto err;

Shouldn't this have been "goto err_unpin;"?

It's not a problem in the backport for 3.2, same code is in the original
patch, just noticed it seems a problem while looking at it; but by what
changelog says the default case is said to not trigger in "practice"
(catch programming error), so I think it doesn't pose a real issue in
practice.

> +	}
> +
>  	ret = intel_ring_begin(ring, 4);
>  	if (ret)
>  		goto err_unpin;
>  
> -	intel_ring_emit(ring, MI_DISPLAY_FLIP_I915 | (intel_crtc->plane << 19));
> +	intel_ring_emit(ring, MI_DISPLAY_FLIP_I915 | plane_bit);
>  	intel_ring_emit(ring, (fb->pitch | obj->tiling_mode));
>  	intel_ring_emit(ring, (obj->gtt_offset));
>  	intel_ring_emit(ring, (MI_NOOP));
> 
> 
> --
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-- 
[]'s
Herton
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