linux-kernel - Re: [PATCH] drm/i915: Discard large BIOS framebuffers causing display corruption.

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Date:   Fri, 7 Jan 2022 13:59:09 +0000
From:   Aditya Garg <gargaditya08@...e.com>
To:     Jani Nikula <jani.nikula@...ux.intel.com>
CC:     "joonas.lahtinen@...ux.intel.com" <joonas.lahtinen@...ux.intel.com>,
        "rodrigo.vivi@...el.com" <rodrigo.vivi@...el.com>,
        "intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/i915: Discard large BIOS framebuffers causing display
 corruption.



> On 07-Jan-2022, at 6:17 PM, Jani Nikula <jani.nikula@...ux.intel.com> wrote:
> 
> On Fri, 07 Jan 2022, Ashish Arora <ashisharora.linux@...look.com> wrote:
>> From: Ashish Arora <ashisharora.linux@...look.com>
>> 
>> On certain 4k panels, the BIOS framebuffer is larger than what panel
>> requires causing display corruption. Introduce a check for the same.
> 
> This is quite thin on details. Is there a bug report?
No bug report, but an issue I am facing myself. This patch seems to fix it.
> 
> Moreover, if this is what we want, this should be combined with the
> conditions that follow resulting in a "!=" check instead of separate "<"
> and ">”.
Sending a version 2
> 
> BR,
> Jani.
> 
> 
> 
>> 
>> Signed-off-by: Ashish Arora <ashisharora.linux@...look.com>
>> ---
>> drivers/gpu/drm/i915/display/intel_fbdev.c | 11 +++++++++++
>> 1 file changed, 11 insertions(+)
>> 
>> diff --git a/drivers/gpu/drm/i915/display/intel_fbdev.c b/drivers/gpu/drm/i915/display/intel_fbdev.c
>> index adc3a81be..f9952e1f8 100644
>> --- a/drivers/gpu/drm/i915/display/intel_fbdev.c
>> +++ b/drivers/gpu/drm/i915/display/intel_fbdev.c
>> @@ -193,6 +193,17 @@ static int intelfb_create(struct drm_fb_helper *helper,
>> 	struct drm_i915_gem_object *obj;
>> 	int ret;
>> 
>> +	if (intel_fb &&
>> +	    (sizes->fb_width < intel_fb->base.width ||
>> +	     sizes->fb_height < intel_fb->base.height)) {
>> +		drm_dbg_kms(&dev_priv->drm,
>> +			    "BIOS fb too large (%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_put(&intel_fb->base);
>> +		intel_fb = ifbdev->fb = NULL;
>> +	}
>> 	if (intel_fb &&
>> 	    (sizes->fb_width > intel_fb->base.width ||
>> 	     sizes->fb_height > intel_fb->base.height)) {
> 
> -- 
> Jani Nikula, Intel Open Source Graphics Center