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

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Message-ID: <Yd7ZnBlU0sjP4qcG@intel.com>
Date:   Wed, 12 Jan 2022 15:37:32 +0200
From:   Ville Syrjälä <ville.syrjala@...ux.intel.com>
To:     Ashish Arora <ashisharora.linux@...look.com>
Cc:     "jani.nikula@...ux.intel.com" <jani.nikula@...ux.intel.com>,
        "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: [Intel-gfx] [PATCH - v3] drm/i915: Discard large BIOS
 framebuffers causing display corruption.

On Tue, Jan 11, 2022 at 07:55:22AM +0000, Ashish Arora wrote:
> From: Ashish Arora <ashisharora.linux@...look.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.

> 
> 
> Signed-off-by: Ashish Arora <ashisharora.linux@...look.com>
> Reviewed-by: Aun-Ali Zaidi <admin@...eit.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