On 26/01/18 00:47, Chris Wilson wrote:
Quoting Daniele Ceraolo Spurio (2018-01-26 00:10:09)
On 24/01/18 09:46, Chris Wilson wrote:
Quoting Daniele Ceraolo Spurio (2018-01-24 17:30:07)
From: Thomas Daniel <thomas.daniel@xxxxxxxxx>
Enhanced Execlists is an upgraded version of execlists which supports
up to 8 ports. The lrcs to be submitted are written to a submit queue
(the ExecLists Submission Queue - ELSQ), which is then loaded on the
HW. When writing to the ELSP register, the lrcs are written cyclically
in the queue from position 0 to position 7. Alternatively, it is
possible to write directly in the individual positions of the queue
using the ELSQC registers. To be able to re-use all the existing code
we're using the latter method and we're currently limiting ourself to
only using 2 elements.
The preemption flow is sligthly different with enhanced execlists, so
this patch turns preemption off temporarily for platforms with ELSQ
while we wait for the new mechanism to land.
v2: Rebase.
v3: Switch from !IS_GEN11 to GEN < 11 (Daniele Ceraolo Spurio).
v4: Use the elsq registers instead of elsp. (Daniele Ceraolo Spurio)
v5: Reword commit, rename regs to be closer to specs, turn off
preemption (Daniele), reuse engine->execlists.elsp (Chris)
v6: use has_logical_ring_elsq to differentiate the new paths
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
Signed-off-by: Thomas Daniel <thomas.daniel@xxxxxxxxx>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_drv.h | 7 ++++++-
drivers/gpu/drm/i915/i915_pci.c | 3 ++-
drivers/gpu/drm/i915/intel_device_info.h | 1 +
drivers/gpu/drm/i915/intel_lrc.c | 35 +++++++++++++++++++++++++++-----
drivers/gpu/drm/i915/intel_lrc.h | 3 +++
drivers/gpu/drm/i915/intel_ringbuffer.h | 6 ++++--
6 files changed, 46 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 8333692..346209a 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2741,8 +2741,13 @@ static inline unsigned int i915_sg_segment_size(void)
#define HAS_LOGICAL_RING_CONTEXTS(dev_priv) \
((dev_priv)->info.has_logical_ring_contexts)
+#define HAS_LOGICAL_RING_ELSQ(dev_priv) \
+ ((dev_priv)->info.has_logical_ring_elsq)
+
+/* XXX: Preemption disabled for ELSQ until support for new flow lands */
#define HAS_LOGICAL_RING_PREEMPTION(dev_priv) \
- ((dev_priv)->info.has_logical_ring_preemption)
+ ((dev_priv)->info.has_logical_ring_preemption && \
+ !HAS_LOGICAL_RING_ELSQ(dev_priv))
It's in the intel_device_info for a reason. I knew I should not have let
Michal turn this into a macro.
You mean setting has_logical_ring_preemption to zero directly? I thought
the policy was to avoid setting things in device_info to values that
don't reflect real HW capabilities and to do the hacks elsewhere.
No, data driven code. intel_device_info was introduced to remove having
heavy predicates so that we could see what will be enabled and what not
in one place.
I still do not see any reason why you don't just make the current
preemption work (it will) and then you can refine it if you prove it
worthwhile.
Just didn't see the worth of it ;). It's not a lot of code but it's in
an hot path and we're most likely going to get rid of it soon as the new
stuff is simpler. I'll put the change together and send it out so we can
evaluate that and see what works better with code at hand.
Is the new stuff going to be any simpler? You still need a preemption
point, so a special submission followed by detecting that in the CS
handler to do the unwind.
And whilst I am here, els is awful. Either stick with elsp and note that
they changed the name (+layout) on icl, or replace it with a generic
name. Spelling it out completely as execlists->execlists_submission is
still better than els, but submit[_reg] (or submit_hw) would be clearer.
-Chris
The elsp still exists on gen11, with a slightly different behavior as
noted in the commit message, that's why I wanted to change the name.
execlists->submit_reg sounds good.
Daniele
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