diff options
| author | Chris Wilson <chris@chris-wilson.co.uk> | 2017-03-21 11:33:20 +0000 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2017-03-21 14:14:55 +0000 |
| commit | 899f6204c0f8117d33226e586d3a630b3cf9bce0 (patch) | |
| tree | 366786612877abc5581dfec13a8ed18e6f26677e /drivers/gpu/drm/i915/intel_lrc.c | |
| parent | 272bce17cc3ef4629e28c38324d81ca72a862115 (diff) | |
drm/i915/execlists: Split the atomic test_and_clear_bit for irq handler
Rather than impose the cost of a locked test before queuing a new
request, reduce it to a simple test_bit() with a following clear_bit()
prior to doing the CSB check. This ensure that if an interrupt does
occur whilst reading from the CSB, we still detect it (the interrupt
would trigger a rescheduling of the tasklet anyway).
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170321113320.2603-1-chris@chris-wilson.co.uk
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Diffstat (limited to 'drivers/gpu/drm/i915/intel_lrc.c')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_lrc.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index dab73e7d9a6b..a88380876ce9 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -530,13 +530,18 @@ static void intel_lrc_irq_handler(unsigned long data) intel_uncore_forcewake_get(dev_priv, engine->fw_domains); - while (test_and_clear_bit(ENGINE_IRQ_EXECLIST, &engine->irq_posted)) { + /* Prefer doing test_and_clear_bit() as a two stage operation to avoid + * imposing the cost of a locked atomic transaction when submitting a + * new request (outside of the context-switch interrupt). + */ + while (test_bit(ENGINE_IRQ_EXECLIST, &engine->irq_posted)) { u32 __iomem *csb_mmio = dev_priv->regs + i915_mmio_reg_offset(RING_CONTEXT_STATUS_PTR(engine)); u32 __iomem *buf = dev_priv->regs + i915_mmio_reg_offset(RING_CONTEXT_STATUS_BUF_LO(engine, 0)); unsigned int csb, head, tail; + clear_bit(ENGINE_IRQ_EXECLIST, &engine->irq_posted); csb = readl(csb_mmio); head = GEN8_CSB_READ_PTR(csb); tail = GEN8_CSB_WRITE_PTR(csb); |