[Intel-gfx] [PATCH 08/17] drm/i915: Don't look at pg_dirty_rings for aliasing ppgtt

[Chris Wilson]

On Tue, Apr 14, 2015 at 07:11:25PM +0200, Daniel Vetter wrote:
> On Tue, Apr 14, 2015 at 05:06:36PM +0100, Chris Wilson wrote:
> > On Tue, Apr 14, 2015 at 05:35:18PM +0200, Daniel Vetter wrote:
> > > We load the ppgtt ptes once per gpu reset/driver load/resume and
> > > that's all that's needed. Note that this only blows up when we're
> > > using the allocate_va_range funcs and not the special-purpose ones
> > > used. With this change we can get rid of that duplication.
> > 
> > Honestly, I would prefer the test to be rewritten so that the
> > information on which vm was being used was passed along and not that
> > magic sprinkled in the middle of nowhere. e.g. execbuffer knows exactly
> > what vm it bound the objects into, and yet towards the end we decide to
> > guess again. Also, I would rather the execbuffer test be moved to
> > i915_gem_context since it is scattering internal knowledge about.
> 
> Yeah I agree that there's more room for cleanup. I've done this minimal
> patch purely to shut up the bogus WARN_ONs when I tried to unify the
> gen6/7 pt alloc code in the next patch. Since it's bogus.

How about:

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index ed9232126644..be0f475ee1e5 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -638,22 +638,14 @@ mi_set_context(struct intel_engine_cs *ring,
 
 static inline bool should_skip_switch(struct intel_engine_cs *ring,
                                      struct intel_context *from,
-                                     struct intel_context *to)
+                                     struct intel_context *to,
+                                     struct i915_hw_ppgtt *ppgtt)
 {
-       struct drm_i915_private *dev_priv = ring->dev->dev_private;
-
        if (to->remap_slice)
                return false;
 
-       if (to->ppgtt) {
-               if (from == to && !test_bit(ring->id,
-                               &to->ppgtt->pd_dirty_rings))
-                       return true;
-       } else if (dev_priv->mm.aliasing_ppgtt) {
-               if (from == to && !test_bit(ring->id,
-                               &dev_priv->mm.aliasing_ppgtt->pd_dirty_rings))
-                       return true;
-       }
+       if (from == to && !test_bit(ring->id, &ppgtt->pd_dirty_rings))
+               return true;
 
        return false;
 }
@@ -661,15 +653,13 @@ static inline bool should_skip_switch(struct intel_engine_cs *ring,
 static bool
 needs_pd_load_pre(struct intel_engine_cs *ring, struct intel_context *to)
 {
-       struct drm_i915_private *dev_priv = ring->dev->dev_private;
-
        if (!to->ppgtt)
                return false;
 
        if (INTEL_INFO(ring->dev)->gen < 8)
                return true;
 
-       if (ring != &dev_priv->ring[RCS])
+       if (ring->id != RCS)
                return true;
 
        return false;
@@ -679,15 +669,13 @@ static bool
 needs_pd_load_post(struct intel_engine_cs *ring, struct intel_context *to,
                u32 hw_flags)
 {
-       struct drm_i915_private *dev_priv = ring->dev->dev_private;
-
        if (!to->ppgtt)
                return false;
 
        if (!IS_GEN8(ring->dev))
                return false;
 
-       if (ring != &dev_priv->ring[RCS])
+       if (ring->id != RCS)
                return false;
 
        if (hw_flags & MI_RESTORE_INHIBIT)
@@ -701,14 +689,15 @@ static int do_switch(struct intel_engine_cs *ring,
 {
        struct drm_i915_private *dev_priv = ring->dev->dev_private;
        struct intel_context *from = ring->last_context;
+       struct i915_hw_ppgtt *ppgtt = to->ppgtt ?: dev_priv->mm.aliasing_ppgtt;
        u32 hw_flags = 0;
        bool uninitialized = false;
        int ret, i;
 
-       if (from != NULL && ring == &dev_priv->ring[RCS])
+       if (from != NULL && ring->id == RCS)
                BUG_ON(from->legacy_hw_ctx.rcs_vma == NULL);
 
-       if (should_skip_switch(ring, from, to))
+       if (should_skip_switch(ring, from, to, ppgtt))
                return 0;
 
        /* Trying to pin first makes error handling easier. */
@@ -851,6 +840,9 @@ done:
        i915_gem_context_reference(to);
        ring->last_context = to;
 
+       WARN(ppgtt->pd_dirty_rings & (1<<ring->id),
+            "%s didn't clear reload\n", ring->name);
+
        if (uninitialized) {
                if (ring->init_context) {
                        ret = ring->init_context(ring, to);
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index ef644e7eaac0..595daecb3283 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1385,13 +1385,6 @@ i915_gem_ringbuffer_submission(struct drm_device *dev, struct drm_file *file,
        if (ret)
                goto error;
 
-       if (ctx->ppgtt)
-               WARN(ctx->ppgtt->pd_dirty_rings & (1<<ring->id),
-                       "%s didn't clear reload\n", ring->name);
-       else if (dev_priv->mm.aliasing_ppgtt)
-               WARN(dev_priv->mm.aliasing_ppgtt->pd_dirty_rings &
-                       (1<<ring->id), "%s didn't clear reload\n", ring->name);
-
        instp_mode = args->flags & I915_EXEC_CONSTANTS_MASK;
        instp_mask = I915_EXEC_CONSTANTS_MASK;
        switch (instp_mode) {


It gets rid of the internal knowledge of address spaces from the execbuf
code, and keeps the symmetry between handling aliasing_ppgtt and
full_ppgtt. (The former should just be a degenerate case where the PD
are all preloaded).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre