[PATCH] drm/i915: Fix the computation of required fb size for pipe

[PATCH] drm/i915: Fix the computation of required fb size for pipe

[Chris Wilson]

The computation of required framebuffer size in

commit d978ef14456a38034f6c0e94a794129501f89200
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date:   Fri Mar 7 08:57:51 2014 -0800

    drm/i915: Wrap the preallocated BIOS framebuffer and preserve for KMS fbcon v12

is too optimistic, and would rely on the invariant fb being
reconstructed to exactly fit each pipe (and probably ignore hardware
limits). Instead, we want to compute the upper bound on what the display
engine will access and ensure that is within the inherited framebuffer.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
---
 drivers/gpu/drm/i915/intel_fbdev.c | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
index 924f75661581..25e81525f9e1 100644
--- a/drivers/gpu/drm/i915/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/intel_fbdev.c
@@ -528,16 +528,29 @@ static bool intel_fbdev_init_bios(struct drm_device *dev,
 
 		/*
 		 * See if the plane fb we found above will fit on this
-		 * pipe.  Note we need to use the selected fb's bpp rather
-		 * than the current pipe's, since they could be different.
+		 * pipe.  Note we need to use the selected fb's pitch and bpp
+		 * rather than the current pipe's, since they differ.
 		 */
-		cur_size = intel_crtc->config.adjusted_mode.crtc_hdisplay *
-			intel_crtc->config.adjusted_mode.crtc_vdisplay;
-		DRM_DEBUG_KMS("pipe %c area: %d\n", pipe_name(intel_crtc->pipe),
+		cur_size = intel_crtc->config.adjusted_mode.crtc_hdisplay;
+		cur_size = cur_size * fb->base.bits_per_pixel / 8;
+		if (fb->base.pitches[0] < cur_size) {
+			DRM_DEBUG_KMS("fb not wide enough for plane %c (%d vs %d)\n",
+				      pipe_name(intel_crtc->pipe),
+				      cur_size, fb->base.pitches[0]);
+			plane_config = NULL;
+			fb = NULL;
+			break;
+		}
+
+		cur_size = intel_crtc->config.adjusted_mode.crtc_vdisplay;
+		cur_size = ALIGN(cur_size, plane_config->tiled ? (IS_GEN2(dev) ? 16 : 8) : 1);
+		cur_size *= fb->base.pitches[0];
+		DRM_DEBUG_KMS("pipe %c area: %dx%d, bpp: %d, size: %d\n",
+			      pipe_name(intel_crtc->pipe),
+			      intel_crtc->config.adjusted_mode.crtc_hdisplay,
+			      intel_crtc->config.adjusted_mode.crtc_vdisplay,
+			      fb->base.bits_per_pixel,
 			      cur_size);
-		cur_size *= fb->base.bits_per_pixel / 8;
-		DRM_DEBUG_KMS("total size %d (bpp %d)\n", cur_size,
-			      fb->base.bits_per_pixel / 8);
 
 		if (cur_size > max_size) {
 			DRM_DEBUG_KMS("fb not big enough for plane %c (%d vs %d)\n",
-- 
1.9.1

Re: [PATCH] drm/i915: Fix the computation of required fb size for pipe

[Chris Wilson]

On Thu, Mar 20, 2014 at 03:11:21PM +0000, Chris Wilson wrote:
> The computation of required framebuffer size in
> 
> commit d978ef14456a38034f6c0e94a794129501f89200
> Author: Jesse Barnes <jbarnes@virtuousgeek.org>
> Date:   Fri Mar 7 08:57:51 2014 -0800
> 
>     drm/i915: Wrap the preallocated BIOS framebuffer and preserve for KMS fbcon v12
> 
> is too optimistic, and would rely on the invariant fb being
> reconstructed to exactly fit each pipe (and probably ignore hardware
> limits). Instead, we want to compute the upper bound on what the display
> engine will access and ensure that is within the inherited framebuffer.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Jesse Barnes <jbarnes@virtuousgeek.org>

Ping. The code is just waiting to explode.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre

Re: [PATCH] drm/i915: Fix the computation of required fb size for pipe

[Daniel Vetter]

On Wed, Apr 02, 2014 at 07:58:18AM +0100, Chris Wilson wrote:
> On Thu, Mar 20, 2014 at 03:11:21PM +0000, Chris Wilson wrote:
> > The computation of required framebuffer size in
> > 
> > commit d978ef14456a38034f6c0e94a794129501f89200
> > Author: Jesse Barnes <jbarnes@virtuousgeek.org>
> > Date:   Fri Mar 7 08:57:51 2014 -0800
> > 
> >     drm/i915: Wrap the preallocated BIOS framebuffer and preserve for KMS fbcon v12
> > 
> > is too optimistic, and would rely on the invariant fb being
> > reconstructed to exactly fit each pipe (and probably ignore hardware
> > limits). Instead, we want to compute the upper bound on what the display
> > engine will access and ensure that is within the inherited framebuffer.
> > 
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> 
> Ping. The code is just waiting to explode.

I kinda hoped it would magically get reviewed by Jesse. Thanks for the
ping, patch is picked up for -fixes.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch

Re: [PATCH] drm/i915: Fix the computation of required fb size for pipe

[Jesse Barnes]

On Wed, 2 Apr 2014 09:10:44 +0200
Daniel Vetter <daniel@ffwll.ch> wrote:

> On Wed, Apr 02, 2014 at 07:58:18AM +0100, Chris Wilson wrote:
> > On Thu, Mar 20, 2014 at 03:11:21PM +0000, Chris Wilson wrote:
> > > The computation of required framebuffer size in
> > > 
> > > commit d978ef14456a38034f6c0e94a794129501f89200
> > > Author: Jesse Barnes <jbarnes@virtuousgeek.org>
> > > Date:   Fri Mar 7 08:57:51 2014 -0800
> > > 
> > >     drm/i915: Wrap the preallocated BIOS framebuffer and preserve for KMS fbcon v12
> > > 
> > > is too optimistic, and would rely on the invariant fb being
> > > reconstructed to exactly fit each pipe (and probably ignore hardware
> > > limits). Instead, we want to compute the upper bound on what the display
> > > engine will access and ensure that is within the inherited framebuffer.
> > > 
> > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > > Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> > 
> > Ping. The code is just waiting to explode.
> 
> I kinda hoped it would magically get reviewed by Jesse. Thanks for the
> ping, patch is picked up for -fixes.

Yeah sorry my brain exploded when looking at this for the nth time so I
kept putting it off.

Looks fine now though, so belated R-b from me.

-- 
Jesse Barnes, Intel Open Source Technology Center