[PATCH 1/2] drm/amdgpu/gmc: always steal the first 32MB of vram for fw hand-over

[Harry Wentland]

On 2018-04-06 09:44 AM, Andrey Grodzovsky wrote:
> 
> 
> On 04/06/2018 09:34 AM, Michel Dänzer wrote:
>> On 2018-04-06 02:39 PM, Andrey Grodzovsky wrote:
>>>> Am 06.04.2018 um 13:23 schrieb Andrey Grodzovsky:
>>>>> Me and Alex talked to a BIOS guys yesterday exactly about that, a
>>>>> dynamic way to query this info from BIOS, he just told us to reserve
>>>>> 32M to cover 4K display.
>> How about reading DCE registers?
> 
> I can try and consult with DAL on this.
> 

Apparently we can read VBIOS allocations from VRAM_UsageByFirmware. Andrey is going to take a look at it. Carving out those allocations is probably better than using GRPH registers to guess VBIOS allocations.

Harry

>>
>>
>>> At least the second patch somehow addresses the memory waste concern,
>>> the reservation will be very transient, during late init the BO will get
>>> freed.
>> Sure, I don't think anybody's concerned about that. My concerns are:
>>
>> * In the cases where we still only reserve 256K, there will likely still
>>    be artifacts during driver initialization.
>>
>> * 32M might still not be enough in some cases, e.g. 5K / 8K displays
> 
> I see your point, as I said above, will again try to find out if there is still a way to know the BIOS FB size.
> 
> Andrey
> 
>>
>>
>> P.S. Please don't top-post.
>>
> 
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