linux-kernel - Re: [PATCH] drm/i915: Discard BIOS framebuffers too small to accommodate chosen mode

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Message-ID: <20140423071125.GS10722@phenom.ffwll.local>
Date:	Wed, 23 Apr 2014 09:11:25 +0200
From:	Daniel Vetter <daniel@...ll.ch>
To:	Chris Wilson <chris@...is-wilson.co.uk>
Cc:	intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	Knut Petersen <Knut_Petersen@...nline.de>,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	Imre Deak <imre.deak@...el.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Jesse Barnes <jbarnes@...tuousgeek.org>
Subject: Re: [PATCH] drm/i915: Discard BIOS framebuffers too small to
 accommodate chosen mode

On Tue, Apr 22, 2014 at 10:05:58PM +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@...tuousgeek.org>
> Date:   Fri Mar 7 08:57:51 2014 -0800
> 
>     drm/i915: Wrap the preallocated BIOS framebuffer and preserve for KMS fbcon v12
> 
> Reported-by: Knut Petersen <Knut_Petersen@...nline.de>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=77767
> Signed-off-by: Chris Wilson <chris@...is-wilson.co.uk>
> Cc: Jesse Barnes <jbarnes@...tuousgeek.org>
> ---
>  drivers/gpu/drm/i915/intel_fbdev.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
> index b16116db6c37..28220ca838df 100644
> --- a/drivers/gpu/drm/i915/intel_fbdev.c
> +++ b/drivers/gpu/drm/i915/intel_fbdev.c
> @@ -133,6 +133,12 @@ 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_framebuffer_reference(&ifbdev->fb->base);
> +		intel_fb = ifbdev->fb = NULL;

Hm, maybe add a
		DRM_DEBUG_KMS("BIOS fb to small, releasing it\n");
here. With or without this is

Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>

> +	}
>  	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
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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