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

[Aditya Garg]

On 07-Jan-2022, at 6:17 PM, Jani Nikula <jani.nikula at linux.intel.com<mailto:jani.nikula at linux.intel.com>> wrote:

On Fri, 07 Jan 2022, Ashish Arora <ashisharora.linux at outlook.com<mailto:ashisharora.linux at outlook.com>> wrote:
From: Ashish Arora <ashisharora.linux at outlook.com<mailto:ashisharora.linux at outlook.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?
I’d like to add on that T2 Macs also require this patch
Probably, Ashish better send a version 2

Moreover, if this is what we want, this should be combined with the
conditions that follow resulting in a "!=" check instead of separate "<"
and ">".

BR,
Jani.




Signed-off-by: Ashish Arora <ashisharora.linux at outlook.com<mailto:ashisharora.linux at outlook.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

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