[PATCH] drm/amdgpu: enable paging queue doorbell support v3

Kuehling, Felix Felix.Kuehling at amd.com
Fri Nov 16 22:58:50 UTC 2018

On 2018-11-16 4:35 p.m., Alex Deucher wrote:
>> +                       ring->doorbell_index += 0x400;
> I don't quite understand how this works.  Why don't we have to adjust
> the doorbell range registers in the nbio code?

NBIO only looks at the lower 12 bits of the doorbell address. So adding
0x400 dwords or 0x1000 bytes has no effect on the doorbell routing.

That's also how we can use SDMA doorbells in our per-process doorbell
pages at higher addresses.


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