On 15/06/2015 06:20, Daniel Vetter wrote:
On Wed, Jun 3, 2015 at 6:14 PM, Ville Syrjälä
<ville.syrjala@xxxxxxxxxxxxxxx> wrote:
I was going to suggest removing the same thing from the
lrc_setup_hardware_status_page(), but after another look it seems we
sometimes call .init_hw() before the context setup. Would be nice to
have a more consistent sequence for init and reset. But anyway the patch
looks OK to me. I verified that we indeed lose this register on GPU
reset.
Yep, this is a mess. And historically _any_ difference between driver
load and gpu reset (or resume fwiw) has lead to hilarious bugs, so
this difference is really troubling to me. Arun, can you please work
on a patch to unify the setup sequence here, so that both driver load
gpu resets work the same way? By the time we're calling gem_init_hw
the default context should have been created already, and hence we
should be able to write to HWS_PGA in ring->init_hw only.
Hi Daniel,
I think the problem in this case was the code to init HWS page after
reset was missing for Gen8+. For Gen7 we are doing this as part of
ring->init_hw.
Gen7:
i915_reset()
+--> i915_gem_init_hw()
+------> ring->init_hw() which is init_render_ring()
+----------> init_ring_common()
+------------> intel_ring_setup_status_page()
Gen8:
i915_reset()
+--> i915_gem_init_hw()
+------> ring->init_hw() which is gen8_init_render_ring()
+--------> gen8_init_common_ring() - I added changes in this function.
We could probably use intel_ring_setup_status_page() for both cases,
does it have to be Gen7 specific?
Also I wonder about resume, where's the HWS_PGA restore for that case?
It is covered.
i915_drm_resume()
+-->i915_gem_init_hw
regards
Arun
-Daniel
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