[Intel-gfx] [PATCH - v3] drm/i915: Discard large BIOS framebuffers causing display corruption.

[Ashish Arora]

> On 12-Jan-2022, at 7:07 PM, Ville Syrjälä <ville.syrjala at linux.intel.com> wrote:
> 
> On Tue, Jan 11, 2022 at 07:55:22AM +0000, Ashish Arora wrote:
>> From: Ashish Arora <ashisharora.linux at outlook.com>
>> 
>> On certain 4k panels and Macs, the BIOS framebuffer is larger than what
>> panel requires causing display corruption. Introduce a check for the same.
> 
> If a larger fb causes corruption then there is a real bug somewhere.
Hi Ville

I and some members of the t2 linux group would like to have more details of this bug.
> 
>> 
>> 
>> Signed-off-by: Ashish Arora <ashisharora.linux at outlook.com>
>> Reviewed-by: Aun-Ali Zaidi <admin at kodeit.net>
>> ---
>> V2 :- Use != instead of < and >
>> V3 :- Mention Macs (Thanks to Orlando)
>> drivers/gpu/drm/i915/display/intel_fbdev.c | 6 +++---
>> 1 file changed, 3 insertions(+), 3 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/i915/display/intel_fbdev.c b/drivers/gpu/drm/i915/display/intel_fbdev.c
>> index 842c04e63..16b1c82b2 100644
>> --- a/drivers/gpu/drm/i915/display/intel_fbdev.c
>> +++ b/drivers/gpu/drm/i915/display/intel_fbdev.c
>> @@ -181,10 +181,10 @@ static int intelfb_create(struct drm_fb_helper *helper,
>> 	int ret;
>> 
>> 	if (intel_fb &&
>> -	    (sizes->fb_width > intel_fb->base.width ||
>> -	     sizes->fb_height > intel_fb->base.height)) {
>> +	    (sizes->fb_width != intel_fb->base.width ||
>> +	     sizes->fb_height != intel_fb->base.height)) {
>> 		drm_dbg_kms(&dev_priv->drm,
>> -			    "BIOS fb too small (%dx%d), we require (%dx%d),"
>> +			    "BIOS fb not valid (%dx%d), we require (%dx%d),"
>> 			    " releasing it\n",
>> 			    intel_fb->base.width, intel_fb->base.height,
>> 			    sizes->fb_width, sizes->fb_height);
>> -- 
>> 2.25.1
>> 
> 
> -- 
> Ville Syrjälä
> Intel