On Fri, 03 Jan 2025, Aditya Garg <[email protected]> wrote:
> Hello maintainers
>
> This bug has been there for a long time, and hasn't been fixed yet. In case 
> the Intel GPU is used as boot GPU on Apple T2 MacBooks, the bottom and right 
> edges of the tty are no longer seen, thus making some text not visible.
>
> It has been reported in almost all Apple T2 MacBooks with Intel GPU, which 
> have the Retina display.
>
> In case of a dual GPU MacBook, if the AMD dGPU is used to boot, the bug no 
> longer exists.
>
> This patch below was submitted 3 years ago, and it fixes this issue.

Please file a bug as described at [1], attaching dmesg from boot with
debugs enabled, etc.

As suggested by Ville in [2], the bug is likely elsewhere, and this just
hides it. A bigger fb shouldn't be a problem, and we shouldn't add this
limitation everywhere because of the issue you're seeing.

BR,
Jani.



[1] https://drm.pages.freedesktop.org/intel-docs/how-to-file-i915-bugs.html

[2] https://lore.kernel.org/r/[email protected]

>
>> On 11 Jan 2022, at 1:25 PM, Ashish Arora <[email protected]> 
>> wrote:
>> 
>> From: Ashish Arora <[email protected]>
>> 
>> On certain 4k panels and Macs, the BIOS framebuffer is larger than what
>> panel requires causing display corruption. Introduce a check for the same.
>> 
>> 
>> Signed-off-by: Ashish Arora <[email protected]>
>> Reviewed-by: Aun-Ali Zaidi <[email protected]>
>> ---
>> 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
>> 
>> 
>> 
>

-- 
Jani Nikula, Intel

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