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drm/i915: Perform Sandybridge BSD tail write under the forcewake 

Since we have a sequence of register reads and writes, we can reduce the
latency of starting the BSD ring by performing all the mmio operations
under the same forcewake wakeref.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1467297225-21379-62-git-send-email-chris@chris-wilson.co.uk
hifive-unleashed-5.1
Chris Wilson 2016-06-30 15:33:45 +01:00
parent 87273b7110
commit 76f8421f2a
2 changed files with 17 additions and 12 deletions
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1
drivers/gpu/drm/i915/i915_drv.h
View File

@ -3882,6 +3882,7 @@ __raw_write(64, q)
*/
#define I915_READ_FW(reg__) __raw_i915_read32(dev_priv, (reg__))
#define I915_WRITE_FW(reg__, val__) __raw_i915_write32(dev_priv, (reg__), (val__))
#define I915_WRITE64_FW(reg__, val__) __raw_i915_write64(dev_priv, (reg__), (val__))
#define POSTING_READ_FW(reg__) (void)I915_READ_FW(reg__)
/* "Broadcast RGB" property */

28
drivers/gpu/drm/i915/intel_ringbuffer.c
View File

@ -2684,34 +2684,38 @@ static void gen6_bsd_ring_write_tail(struct intel_engine_cs *engine,
{
struct drm_i915_private *dev_priv = engine->i915;
intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
/* Every tail move must follow the sequence below */
/* Disable notification that the ring is IDLE. The GT
* will then assume that it is busy and bring it out of rc6.
*/
I915_WRITE(GEN6_BSD_SLEEP_PSMI_CONTROL,
_MASKED_BIT_ENABLE(GEN6_BSD_SLEEP_MSG_DISABLE));
I915_WRITE_FW(GEN6_BSD_SLEEP_PSMI_CONTROL,
_MASKED_BIT_ENABLE(GEN6_BSD_SLEEP_MSG_DISABLE));
/* Clear the context id. Here be magic! */
I915_WRITE64(GEN6_BSD_RNCID, 0x0);
I915_WRITE64_FW(GEN6_BSD_RNCID, 0x0);
/* Wait for the ring not to be idle, i.e. for it to wake up. */
if (intel_wait_for_register(dev_priv,
GEN6_BSD_SLEEP_PSMI_CONTROL,
GEN6_BSD_SLEEP_INDICATOR,
0,
50))
if (intel_wait_for_register_fw(dev_priv,
GEN6_BSD_SLEEP_PSMI_CONTROL,
GEN6_BSD_SLEEP_INDICATOR,
0,
50))
DRM_ERROR("timed out waiting for the BSD ring to wake up\n");
/* Now that the ring is fully powered up, update the tail */
I915_WRITE_TAIL(engine, value);
POSTING_READ(RING_TAIL(engine->mmio_base));
I915_WRITE_FW(RING_TAIL(engine->mmio_base), value);
POSTING_READ_FW(RING_TAIL(engine->mmio_base));
/* Let the ring send IDLE messages to the GT again,
* and so let it sleep to conserve power when idle.
*/
I915_WRITE(GEN6_BSD_SLEEP_PSMI_CONTROL,
_MASKED_BIT_DISABLE(GEN6_BSD_SLEEP_MSG_DISABLE));
I915_WRITE_FW(GEN6_BSD_SLEEP_PSMI_CONTROL,
_MASKED_BIT_DISABLE(GEN6_BSD_SLEEP_MSG_DISABLE));
intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
}
static int gen6_bsd_ring_flush(struct drm_i915_gem_request *req,