linux-kernel - Re: [PATCH] drm/i915/fbdev: Discard large BIOS framebuffers

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Message-ID: <87ldv4pe1u.fsf@intel.com>
Date: Tue, 21 Jan 2025 14:05:49 +0200
From: Jani Nikula <jani.nikula@...ux.intel.com>
To: Atharva Tiwari <evepolonium@...il.com>
Cc: evepolonium@...il.com, Rodrigo Vivi <rodrigo.vivi@...el.com>, Joonas
 Lahtinen <joonas.lahtinen@...ux.intel.com>, Tvrtko Ursulin
 <tursulin@...ulin.net>, David Airlie <airlied@...il.com>, Simona Vetter
 <simona@...ll.ch>, intel-gfx@...ts.freedesktop.org,
 intel-xe@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org, Ville Syrjala
 <ville.syrjala@...ux.intel.com>
Subject: Re: [PATCH] drm/i915/fbdev: Discard large BIOS framebuffers

On Tue, 21 Jan 2025, Atharva Tiwari <evepolonium@...il.com> wrote:
> On certain 4K panels, the BIOS framebuffer
> exceeds the panel's required dimensions,
> leading to display corruption.
> This patch introduces a validation check to address the issue.
>
> Signed-off-by: Atharva Tiwari <evepolonium@...il.com>

See [1], [2], and [3].

Please add your dmesg with debugs enabled to [3].

BR,
Jani.


[1] https://lore.kernel.org/r/31D69334-DEF9-41B7-968B-B847796926FF@outlook.com

[2] https://lore.kernel.org/r/Yd7ZnBlU0sjP4qcG@intel.com

[3] https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13466


> ---
>  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 00852ff5b247..e8cf06772c31 100644
> --- a/drivers/gpu/drm/i915/display/intel_fbdev.c
> +++ b/drivers/gpu/drm/i915/display/intel_fbdev.c
> @@ -197,10 +197,10 @@ static int intelfb_create(struct drm_fb_helper *helper,
>  	ifbdev->fb = NULL;
>  
>  	if (fb &&
> -	    (sizes->fb_width > fb->base.width ||
> -	     sizes->fb_height > fb->base.height)) {
> +	    (sizes->fb_width != fb->base.width ||
> +	     sizes->fb_height != fb->base.height)) {
>  		drm_dbg_kms(&dev_priv->drm,
> -			    "BIOS fb too small (%dx%d), we require (%dx%d),"
> +			    "BIOS fb dimensions mismatch (%dx%d), we require (%dx%d),"
>  			    " releasing it\n",
>  			    fb->base.width, fb->base.height,
>  			    sizes->fb_width, sizes->fb_height);

-- 
Jani Nikula, Intel