Previously we dropped the association of a context to a ring. It is
however very important to know which ring a context ran on (we could
have reused the other member, but I was nitpicky).
This is very important when we switch address spaces, which unlike
context objects, do change per ring.
As an example, if we have:
RCS BCS
ctx A
ctx A
ctx B
ctx B
Without tracking the last ring B ran on, we wouldn't know to switch the
address space on BCS in the last row.
Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
---
drivers/gpu/drm/i915/i915_drv.h | 1 +
drivers/gpu/drm/i915/i915_gem_context.c | 3 ++-
2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index fa8a432..b1b31c0 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -586,6 +586,7 @@ struct i915_hw_context {
struct i915_ctx_hang_stats hang_stats;
struct i915_hw_ppgtt ppgtt;
+ struct intel_ring_buffer *last_ring;
};
struct i915_fbc {
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index faddf43..e20ece6 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -535,7 +535,7 @@ static int do_switch(struct intel_ring_buffer *ring,
BUG_ON(from->obj->pin_count == 0);
}
- if (from == to)
+ if (from == to && from->last_ring == ring)
return 0;
if (ring != &dev_priv->ring[RCS] && from) {
@@ -616,6 +616,7 @@ done:
i915_gem_context_reference(to);
ring->last_context = to;
to->is_initialized = true;
+ to->last_ring = ring;
return 0;
}
--
1.8.3.1
