Re: [RFC 13/28] drm/i915: Convert i915_gem_init_hw to intel_gt

Chris Wilson
2019-06-13T16:30:57Z

Quoting Tvrtko Ursulin (2019-06-13 17:11:43)
>
> On 13/06/2019 14:59, Chris Wilson wrote:
> > Quoting Tvrtko Ursulin (2019-06-13 14:35:24)
> >> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> >>
> >> More removal of implicit dev_priv from using old mmio accessors.
> >>
> >> Actually the top level function remains but is split into a part which
> >> writes to i915 and part which operates on intel_gt in order to initialize
> >> the hardware.
> >>
> >> GuC and engines are the only odd ones out remaining.
> >>
> >> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> >> ---
> >> drivers/gpu/drm/i915/i915_gem.c | 66 ++++++++++++++++++++-------------
> >> 1 file changed, 40 insertions(+), 26 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> >> index e54cd30534dc..b6f450e782e7 100644
> >> --- a/drivers/gpu/drm/i915/i915_gem.c
> >> +++ b/drivers/gpu/drm/i915/i915_gem.c
> >> @@ -1234,28 +1234,32 @@ static void init_unused_rings(struct intel_gt *gt)
> >> }
> >> }
> >>
> >> -int i915_gem_init_hw(struct drm_i915_private *dev_priv)
> >> +static int init_hw(struct intel_gt *gt)
> >> {
> >> + struct drm_i915_private *i915 = gt->i915;
> >> + struct intel_uncore *uncore = gt->uncore;
> >> int ret;
> >>
> >> - dev_priv->gt.last_init_time = ktime_get();
> >> + gt->last_init_time = ktime_get();
> >>
> >> /* Double layer security blanket, see i915_gem_init() */
> >> - intel_uncore_forcewake_get(&dev_priv->uncore, FORCEWAKE_ALL);
> >> + intel_uncore_forcewake_get(uncore, FORCEWAKE_ALL);
> >>
> >> - if (HAS_EDRAM(dev_priv) && INTEL_GEN(dev_priv) < 9)
> >> - I915_WRITE(HSW_IDICR, I915_READ(HSW_IDICR) | IDIHASHMSK(0xf));
> >> + if (HAS_EDRAM(i915) && INTEL_GEN(i915) < 9)
> >> + intel_uncore_rmw(uncore, HSW_IDICR, 0, IDIHASHMSK(0xf));
> >>
> >> - if (IS_HASWELL(dev_priv))
> >> - I915_WRITE(MI_PREDICATE_RESULT_2, IS_HSW_GT3(dev_priv) ?
> >> - LOWER_SLICE_ENABLED : LOWER_SLICE_DISABLED);
> >> + if (IS_HASWELL(i915))
> >> + intel_uncore_write(uncore,
> >> + MI_PREDICATE_RESULT_2,
> >> + IS_HSW_GT3(i915) ?
> >> + LOWER_SLICE_ENABLED : LOWER_SLICE_DISABLED);
> >>
> >> /* Apply the GT workarounds... */
> >> - intel_gt_apply_workarounds(&dev_priv->gt);
> >> + intel_gt_apply_workarounds(gt);
> >
> > Would it be worth moving the above mmio into workarounds? Whilst you are
> > doing some spring cleaning :)
>
> To GT workarounds? Are the above two workarounds? Do they have an
> official designation?

To intel_gt_workarounds_apply, I'm sure you can find something ;)

> >> /* ...and determine whether they are sticking. */
> >> - intel_gt_verify_workarounds(&dev_priv->gt, "init");
> >> + intel_gt_verify_workarounds(gt, "init");
> >>
> >> - intel_gt_init_swizzling(&dev_priv->gt);
> >> + intel_gt_init_swizzling(gt);
> >>
> >> /*
> >> * At least 830 can leave some of the unused rings
> >> @@ -1263,48 +1267,58 @@ int i915_gem_init_hw(struct drm_i915_private *dev_priv)
> >> * will prevent c3 entry. Makes sure all unused rings
> >> * are totally idle.
> >> */
> >> - init_unused_rings(&dev_priv->gt);
> >> -
> >> - BUG_ON(!dev_priv->kernel_context);
> >> - ret = i915_terminally_wedged(dev_priv);
> >> - if (ret)
> >> - goto out;
> >> + init_unused_rings(gt);
> >>
> >> - ret = i915_ppgtt_init_hw(&dev_priv->gt);
> >> + ret = i915_ppgtt_init_hw(gt);
> >> if (ret) {
> >> DRM_ERROR("Enabling PPGTT failed (%d)\n", ret);
> >> goto out;
> >> }
> >>
> >> - ret = intel_wopcm_init_hw(&dev_priv->wopcm);
> >> + ret = intel_wopcm_init_hw(&i915->wopcm);
> >> if (ret) {
> >> DRM_ERROR("Enabling WOPCM failed (%d)\n", ret);
> >> goto out;
> >> }
> >>
> >> /* We can't enable contexts until all firmware is loaded */
> >> - ret = intel_uc_init_hw(dev_priv);
> >> + ret = intel_uc_init_hw(i915);
> >
> > Sorting out the uc layering is an ongoing task. I think it probably
> > means our init_hw needs splitting.
>
> I think guc and huc could be made children of intel_gt so this could be
> changed to take gt. It's a lot of code which I am not sure has much yet
> to live so I opted not to touch it.

I can go either way. There are a few hooks into e.g. i915_ggtt, but
mostly it is a different means of driving HW (by passing through to a
second driver of our HW, grumble) via a separate communication
channel. On the whole, I think it replaces gt/.

In passing, as we move i915_ggtt/i915_ppgtt beneath gt/, we should also
consider using the intel_ prefix. The goal is that these are the HW
interface for tracking the page tables with the i915_gem_context being
the API interface. (And if the GEM vm api grows more we should
introduce a i915_gem_vm/gtt wrapper around intel_ppgtt.)

> >> if (ret) {
> >> DRM_ERROR("Enabling uc failed (%d)\n", ret);
> >> goto out;
> >> }
> >>
> >> - intel_mocs_init_l3cc_table(&dev_priv->gt);
> >> + intel_mocs_init_l3cc_table(gt);
> >>
> >> /* Only when the HW is re-initialised, can we replay the requests */
> >> - ret = intel_engines_resume(dev_priv);
> >> + ret = intel_engines_resume(i915);
> >> if (ret)
> >> goto cleanup_uc;
> >>
> >> - intel_uncore_forcewake_put(&dev_priv->uncore, FORCEWAKE_ALL);
> >> + intel_uncore_forcewake_put(uncore, FORCEWAKE_ALL);
> >>
> >> - intel_engines_set_scheduler_caps(dev_priv);
> >> return 0;
> >>
> >> cleanup_uc:
> >> - intel_uc_fini_hw(dev_priv);
> >> + intel_uc_fini_hw(i915);
> >> out:
> >> - intel_uncore_forcewake_put(&dev_priv->uncore, FORCEWAKE_ALL);
> >> + intel_uncore_forcewake_put(uncore, FORCEWAKE_ALL);
> >> +
> >> + return ret;
> >> +}
> >> +
> >> +int i915_gem_init_hw(struct drm_i915_private *i915)
> >
> > Do we also start to recognise this as i915_init_hw()? This is the driver
> > talking to the intel_gt and friends, not the driver setting up the GEM
> > api.
>
> Not sure. There are some GEM bits inside like wedged status and
> scheduler caps. So it sounds passable to leave it like it is for now.

wedged is mostly our response to HW, and is controlled by
gt/intel_reset.c. But we also use to disable the GEM uAPI. However that
is just the API layer looking at the underlying HW state and saying "no can do".
Hopefully.

i915->gpu_error is definitely an interesting beast. I actually think it
doesn't belong inside i915->gt as it is a separate HW snapshot for
different API, but not actually a part of driving the HW.

The caps.sched are an interesting wart, we are summarising the gt
features and they change depending on how we mistreat gt (wedged).
-Chris