linux-kernel - Re: [BUG] The bottom and right edges on the tty are not shown on Apple T2 MacBooks with Retina display

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Message-ID: <87bjwom1be.fsf@intel.com>
Date: Fri, 03 Jan 2025 16:14:45 +0200
From: Jani Nikula <jani.nikula@...ux.intel.com>
To: Aditya Garg <gargaditya08@...e.com>, Ashish Arora
 <ashisharora.linux@...look.com>
Cc: "joonas.lahtinen@...ux.intel.com" <joonas.lahtinen@...ux.intel.com>,
 "rodrigo.vivi@...el.com" <rodrigo.vivi@...el.com>,
 "ville.syrjala@...ux.intel.com" <ville.syrjala@...ux.intel.com>,
 "intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>, Linux
 Kernel Mailing List <linux-kernel@...r.kernel.org>, Orlando Chamberlain
 <orlandoch.dev@...il.com>
Subject: Re: [BUG] The bottom and right edges on the tty are not shown on
 Apple T2 MacBooks with Retina display

On Fri, 03 Jan 2025, Aditya Garg <gargaditya08@...e.com> 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/Yd7ZnBlU0sjP4qcG@intel.com

>
>> On 11 Jan 2022, at 1:25 PM, Ashish Arora <ashisharora.linux@...look.com> 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.
>> 
>> 
>> 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
>> 
>> 
>> 
>

-- 
Jani Nikula, Intel