[PATCH] drm/amdgpu: don't limit gtt size on apus

[Paul Menzel]

Dear Linux folks,


Am 05.01.21 um 23:31 schrieb Joshua Ashton:
> On 1/5/21 10:10 PM, Alex Deucher wrote:
>> On Tue, Jan 5, 2021 at 5:05 PM Joshua Ashton <joshua at froggi.es> wrote:
>>>
>>> Since commit 24562523688b ("Revert "drm/amd/amdgpu: set gtt size
>>> according to system memory size only""), the GTT size was limited by
>>> 3GiB or VRAM size.
>>
>> The commit in question was to fix a hang with certain tests on APUs.
>> That should be tested again before we re-enable this.  If it is fixed,
>> we should just revert the revert rather than special case dGPUs.

> I think the commit before the revert (ba851eed895c) has some fundamental 
> problems:

For the record, I can’t find commit ba851eed895c in my git repository. 
It seems to be commit 5f97fc0e03 [1]. (I wonder how that happened, but 
it was in 2017, so hopefully the processes improved.)

> It was always specifying max(3GiB, 3/4ths RAM) of GTT, even if that 
> wouldn't fit into say, 1GiB or 2GiB of available RAM.
> 
> Limiting GTT to min(max(3GiB, VRAM), 3/4ths RAM) size on dGPUs makes 
> sense also and is a sensible limit to avoid silly situations with 
> overallocation and potential OOM.
> 
> This patch solves both of those issues.


Kind regards,

Paul


[1]: 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5f97fc0e032594212459f63e9c6229cd79ccb697