[radeon]Question about create ring BO in VRAM
chenj at lemote.com
Sat Nov 5 01:26:27 PDT 2011
2011/11/5 Alex Deucher <alexdeucher at gmail.com>:
> On Fri, Nov 4, 2011 at 10:26 AM, Chen Jie <chenj at lemote.com> wrote:
>> Hi all,
>> I tried to create/pin ring BO in VRAM instead of GTT to debug some
>> ring-related problems. After I did this, it rendered a black screen in
>> X (on a X86 RS780E board), but radeon.test passed.
>> 'ps aux' shows X uninterruptibly sleeps on radeon.
>> Curious why this does not work?
> The tricky part is dealing with the HDP cache. Access to vram via the
> PCI FB BAR goes through the HDP cache, you have to make sure it's
> flushed properly before the GPU starts using the data there. To flush
> it, either read back from vram, or write 1 to the
> HDP_MEM_COHERENCY_FLUSH_CNTL register. We generally don't recommend
> putting the ring in vram.
Get it, thanks.
After add HDP cache flush in r600_cp_commit(), it works fine.
-- Chen Jie
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