On Wed, Jan 06, 2010 at 01:57:08PM -0500, Alex Deucher wrote:
> On Wed, Jan 6, 2010 at 1:29 PM, Jerome Glisse <[email protected]> wrote:
> > R300 family will hard lockup if host path read cache flush is
> > done through MMIO to HOST_PATH_CNTL. But scheduling same flush
> > through ring seems harmless. This patch remove the hdp_flush
> > callback and add a flush after each fence emission which means
> > a flush after each IB schedule. Thus we should have same behavior
> > without the hard lockup.
> 
> We really only need to flush the HDP cache after rendering to vram (or
> UMA in the IGP case).  Wouldn't it be better to just flush in those
> cases?  We may want to use the hdp flush callback after sw access to
> vram as well, so having a separate hdp callback might be better.  See
> other comments inline below.
> 
> Alex

Do you know if always flushing impact performances ? I didn't benchmarked
but i think arena did have same fps before or after the patch. The idea
of the patch was to have the same behavior accross different family and
avoid having fake callback.
> 
> On r6xx+, mmio should be ok.
> 

Yeah i did change every family just for consistency.

> > @@ -1785,6 +1780,8 @@ void r600_fence_ring_emit(struct radeon_device *rdev,
> >        radeon_ring_write(rdev, PACKET3(PACKET3_SET_CONFIG_REG, 1));
> >        radeon_ring_write(rdev, ((rdev->fence_drv.scratch_reg - 
> > PACKET3_SET_CONFIG_REG_OFFSET) >> 2));
> >        radeon_ring_write(rdev, fence->seq);
> > +       radeon_ring_write(rdev, 
> > PACKET0(R_005480_HDP_MEM_COHERENCY_FLUSH_CNTL, 0));
> > +       radeon_ring_write(rdev, 1);
> 
> If you add additional packets here, you'll need to adjust the fence
> counts in r600_blit_prepare_copy() in r600_blit_kms.c as well.
> 

Will check that, what i did in others part of the code was to always ask
for a lot of room in the ring (64 dwords) so that i could grow what is
in fence emit or ib schedule without having to worry. I will change r600
path to do the same. It doesn't hurt to ask for more dword than needed.

Cheers,
Jerome

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