[Intel-gfx] [PATCH v2] drm/i915: Rework GPU reset sequence to match driver load & thaw

[Daniel Vetter]

On Fri, Aug 15, 2014 at 3:33 PM, Mcaulay, Alistair
<alistair.mcaulay at intel.com> wrote:
> below is the basic code path of a reset which has been changed by my patch:
>
> i915_reset()
> {
>         ....
>         i915_gem_reset() -> This used to call i915_gem_context_reset(), which has now been removed.
>         .....
>         i915_gem_init_hw()
>                 .....
>                 i915_gem_context_enable() -> This used to return during reset. Now it doesn't
>                 .....
>                         for each ring, i915_switch_context(default)
>                                 do_switch();
>                 .....
>
>         .....
> }
>
> " I am with Daniel on this one. I don't understand how can we throw everything in here away."
> Did you maybe mean Ben?
> Daniel, I thought you were happy with the implementation, and V2 fixed your last concern, could you please comment.

I'm happy with the underlying fix, but I didn't check all the details
and instead signed up Mika for that. Helps me scale and also makes
sure that more people understand tricky parts.

> " We need to force hw to switch to a working context, after reset, so that our internal state tracking matches."
> I believe this patch does that using i915_switch_context, rather than the hacky i915_gem_context_reset()

I'm half in a plane already, so I'll leave it to you and Mika to
figure this out. Maybe the only thing missing is a bit more
explanation in the commit message why exactly we can remove all that
code. On a quick glance both Mika's concern and your reply make sense.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch