[PATCH 03/13] drm/i915: Avoid invariant conditionals in lrc interrupt handler

Tvrtko Ursulin
2016-01-08T11:29:59Z

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

There is no need to check on what Gen we are running on every
interrupt and every command submission. We can instead set up
some of that when engines are initialized, store it in the
engine structure and use it directly at runtime.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
drivers/gpu/drm/i915/intel_lrc.c | 36 ++++++++++++++++++---------------
drivers/gpu/drm/i915/intel_ringbuffer.h | 2 ++
2 files changed, 22 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 8b6071fcd743..84977a6e6f3f 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -298,29 +298,15 @@ uint64_t intel_lr_context_descriptor(struct intel_context *ctx,
struct intel_engine_cs *ring)
{
struct drm_i915_gem_object *ctx_obj = ctx->engine[ring->id].state;
- uint64_t desc;
+ uint64_t desc = ring->ctx_desc_template;
uint64_t lrca = i915_gem_obj_ggtt_offset(ctx_obj) +
LRC_PPHWSP_PN * PAGE_SIZE;

WARN_ON(lrca & 0xFFFFFFFF00000FFFULL);

- desc = GEN8_CTX_VALID;
- desc |= GEN8_CTX_ADDRESSING_MODE(dev) << GEN8_CTX_ADDRESSING_MODE_SHIFT;
- if (IS_GEN8(ctx_obj->base.dev))
- desc |= GEN8_CTX_L3LLC_COHERENT;
- desc |= GEN8_CTX_PRIVILEGE;
desc |= lrca;
desc |= (u64)intel_execlists_ctx_id(ctx_obj) << GEN8_CTX_ID_SHIFT;

- /* TODO: WaDisableLiteRestore when we start using semaphore
- * signalling between Command Streamers */
- /* desc |= GEN8_CTX_FORCE_RESTORE; */
-
- /* WaEnableForceRestoreInCtxtDescForVCS:skl */
- /* WaEnableForceRestoreInCtxtDescForVCS:bxt */
- if (disable_lite_restore_wa(ring))
- desc |= GEN8_CTX_FORCE_RESTORE;
-
return desc;
}

@@ -556,7 +542,7 @@ void intel_lrc_irq_handler(struct intel_engine_cs *ring)
}
}

- if (disable_lite_restore_wa(ring)) {
+ if (ring->disable_lite_restore_wa) {
/* Prevent a ctx to preempt itself */
if ((status & GEN8_CTX_STATUS_ACTIVE_IDLE) &&
(submit_contexts != 0))
@@ -1980,6 +1966,24 @@ static int logical_ring_init(struct drm_device *dev, struct intel_engine_cs *rin
goto error;
}

+ ring->disable_lite_restore_wa = disable_lite_restore_wa(ring);
+
+ ring->ctx_desc_template = GEN8_CTX_VALID;
+ ring->ctx_desc_template |= GEN8_CTX_ADDRESSING_MODE(dev) <<
+ GEN8_CTX_ADDRESSING_MODE_SHIFT;
+ if (IS_GEN8(dev))
+ ring->ctx_desc_template |= GEN8_CTX_L3LLC_COHERENT;
+ ring->ctx_desc_template |= GEN8_CTX_PRIVILEGE;
+
+ /* TODO: WaDisableLiteRestore when we start using semaphore
+ * signalling between Command Streamers */
+ /* ring->ctx_desc_template |= GEN8_CTX_FORCE_RESTORE; */
+
+ /* WaEnableForceRestoreInCtxtDescForVCS:skl */
+ /* WaEnableForceRestoreInCtxtDescForVCS:bxt */
+ if (ring->disable_lite_restore_wa)
+ ring->ctx_desc_template |= GEN8_CTX_FORCE_RESTORE;
+
return 0;

error:
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 49574ffe54bc..0b91a4b77359 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -268,6 +268,8 @@ struct intel_engine_cs {
struct list_head execlist_queue;
struct list_head execlist_retired_req_list;
u8 next_context_status_buffer;
+ bool disable_lite_restore_wa;
+ u32 ctx_desc_template;
u32 irq_keep_mask; /* bitmask for interrupts that should not be masked */
int (*emit_request)(struct drm_i915_gem_request *request);
int (*emit_flush)(struct drm_i915_gem_request *request,
--
1.9.1