[Intel-gfx] [PATCH 5/7] drm/i915/gt: Ignore stale context state upon resume

[Chris Wilson]

Quoting Matthew Auld (2019-12-30 16:06:47)
> On Sun, 29 Dec 2019 at 18:32, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> >  static const struct intel_context_ops execlists_context_ops = {
> > @@ -3968,7 +3982,6 @@ static void init_common_reg_state(u32 * const regs,
> >                                             CTX_CTRL_RS_CTX_ENABLE);
> >
> >         regs[CTX_RING_CTL] = RING_CTL_SIZE(ring->size) | RING_VALID;
> > -       regs[CTX_BB_STATE] = RING_BB_PPGTT;
> 
> Zero clue what that does...

It's supposed to be a readonly bit that shows the state of the current
batch buffer, and is supposed to be only set by MI_BB_START. Broadwell
and Braswell disagree with the bspec. C'est la vie.

I broke it out into a separate patch for clarity.
-Chris