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drm/i915: Avoid sleeping inside per-engine reset

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Only sleep and repeat when asked for a full device reset (ALL_ENGINES)
and avoid using sleeping waits when asked for a per-engine reset. The
goal is to be able to use a per-engine reset from hardirq/softirq/timer
context. A consequence is that our individual wait timeouts are a
thousand times shorter, on the order of a hundred microseconds rather
than hundreds of millisecond. This may make hitting the timeouts more
common, but hopefully the fallover to the full-device reset will be
sufficient to pick up the pieces.

Note, that the sleeps inside older gen (pre-gen8) have been left as they
are only used in full device reset mode.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Michał Winiarski <michal.winiarski@intel.com>
CC: Michel Thierry <michel.thierry@intel.com>
Cc: Jeff McGee <jeff.mcgee@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Michel Thierry <michel.thierry@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180329224519.13598-1-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2018-03-29 23:45:18 +01:00
parent 9bd9be6660
commit 5807e1c21d
1 changed files with 34 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

51
drivers/gpu/drm/i915/intel_uncore.c
View File

@ -1702,11 +1702,10 @@ static void gen3_stop_engine(struct intel_engine_cs *engine)
const i915_reg_t mode = RING_MI_MODE(base);
I915_WRITE_FW(mode, _MASKED_BIT_ENABLE(STOP_RING));
if (intel_wait_for_register_fw(dev_priv,
mode,
MODE_IDLE,
MODE_IDLE,
500))
if (__intel_wait_for_register_fw(dev_priv,
mode, MODE_IDLE, MODE_IDLE,
500, 0,
NULL))
DRM_DEBUG_DRIVER("%s: timed out on STOP_RING\n",
engine->name);
@ -1860,9 +1859,10 @@ static int gen6_hw_domain_reset(struct drm_i915_private *dev_priv,
__raw_i915_write32(dev_priv, GEN6_GDRST, hw_domain_mask);
/* Wait for the device to ack the reset requests */
err = intel_wait_for_register_fw(dev_priv,
GEN6_GDRST, hw_domain_mask, 0,
500);
err = __intel_wait_for_register_fw(dev_priv,
GEN6_GDRST, hw_domain_mask, 0,
500, 0,
NULL);
if (err)
DRM_DEBUG_DRIVER("Wait for 0x%08x engines reset failed\n",
hw_domain_mask);
@ -2027,11 +2027,12 @@ static int gen8_reset_engine_start(struct intel_engine_cs *engine)
I915_WRITE_FW(RING_RESET_CTL(engine->mmio_base),
_MASKED_BIT_ENABLE(RESET_CTL_REQUEST_RESET));
ret = intel_wait_for_register_fw(dev_priv,
RING_RESET_CTL(engine->mmio_base),
RESET_CTL_READY_TO_RESET,
RESET_CTL_READY_TO_RESET,
700);
ret = __intel_wait_for_register_fw(dev_priv,
RING_RESET_CTL(engine->mmio_base),
RESET_CTL_READY_TO_RESET,
RESET_CTL_READY_TO_RESET,
700, 0,
NULL);
if (ret)
DRM_ERROR("%s: reset request timeout\n", engine->name);
@ -2094,15 +2095,31 @@ int intel_gpu_reset(struct drm_i915_private *dev_priv, unsigned engine_mask)
int retry;
int ret;
might_sleep();
/*
* We want to perform per-engine reset from atomic context (e.g.
* softirq), which imposes the constraint that we cannot sleep.
* However, experience suggests that spending a bit of time waiting
* for a reset helps in various cases, so for a full-device reset
* we apply the opposite rule and wait if we want to. As we should
* always follow up a failed per-engine reset with a full device reset,
* being a little faster, stricter and more error prone for the
* atomic case seems an acceptable compromise.
*
* Unfortunately this leads to a bimodal routine, when the goal was
* to have a single reset function that worked for resetting any
* number of engines simultaneously.
*/
might_sleep_if(engine_mask == ALL_ENGINES);
/* If the power well sleeps during the reset, the reset
/*
* If the power well sleeps during the reset, the reset
* request may be dropped and never completes (causing -EIO).
*/
intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
for (retry = 0; retry < 3; retry++) {
/* We stop engines, otherwise we might get failed reset and a
/*
* We stop engines, otherwise we might get failed reset and a
* dead gpu (on elk). Also as modern gpu as kbl can suffer
* from system hang if batchbuffer is progressing when
* the reset is issued, regardless of READY_TO_RESET ack.
@ -2120,7 +2137,7 @@ int intel_gpu_reset(struct drm_i915_private *dev_priv, unsigned engine_mask)
GEM_TRACE("engine_mask=%x\n", engine_mask);
ret = reset(dev_priv, engine_mask);
}
if (ret != -ETIMEDOUT)
if (ret != -ETIMEDOUT || engine_mask != ALL_ENGINES)
break;
cond_resched();