[Intel-gfx] [PATCH] drm/i915: Discard BIOS framebuffers too small to accommodate chosen mode

[Ville Syrjälä]

On Wed, Apr 23, 2014 at 08:54:31AM +0100, Chris Wilson wrote:
> If the inherited BIOS framebuffer is smaller than the mode selected for
> fbdev, then if we continue to use it then we cause display corruption as
> we do not setup the panel fitter to upscale.
> 
> Regression from commit d978ef14456a38034f6c0e94a794129501f89200
> Author: Jesse Barnes <jbarnes at virtuousgeek.org>
> Date:   Fri Mar 7 08:57:51 2014 -0800
> 
>     drm/i915: Wrap the preallocated BIOS framebuffer and preserve for KMS fbcon v12
> 
> v2: Add a debug message to track the discard of the BIOS fb.
> v3: Ville pointed out the difference between ref/unref
> 
> Reported-by: Knut Petersen <Knut_Petersen at t-online.de>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=77767
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Jesse Barnes <jbarnes at virtuousgeek.org>
> Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

> ---
>  drivers/gpu/drm/i915/intel_fbdev.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
> index b16116db6c37..fbe7941f88c8 100644
> --- a/drivers/gpu/drm/i915/intel_fbdev.c
> +++ b/drivers/gpu/drm/i915/intel_fbdev.c
> @@ -133,6 +133,16 @@ static int intelfb_create(struct drm_fb_helper *helper,
>  
>  	mutex_lock(&dev->struct_mutex);
>  
> +	if (intel_fb &&
> +	    (sizes->fb_width > intel_fb->base.width ||
> +	     sizes->fb_height > intel_fb->base.height)) {
> +		DRM_DEBUG_KMS("BIOS fb too small (%dx%d), we require (%dx%d),"
> +			      " releasing it\n",
> +			      intel_fb->base.width, intel_fb->base.height,
> +			      sizes->fb_width, sizes->fb_height);
> +		drm_framebuffer_unreference(&intel_fb->base);
> +		intel_fb = ifbdev->fb = NULL;
> +	}
>  	if (!intel_fb || WARN_ON(!intel_fb->obj)) {
>  		DRM_DEBUG_KMS("no BIOS fb, allocating a new one\n");
>  		ret = intelfb_alloc(helper, sizes);
> -- 
> 1.9.2
> 
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-- 
Ville Syrjälä
Intel OTC