From bb5db7e1601b368e7aad5e4ceded75de70f6fddb Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Mon, 22 Jan 2018 10:07:14 +0000 Subject: [PATCH] drm/i915/execlists: Skip forcewake for ELSP submission Now that we can read the CSB from the HWSP, we may avoid having to perform mmio reads entirely and so forgo the rigmarole of the forcewake dance. v2: Include forcewake hint for GEM_TRACE readback of mmio. If we don't hold fw ourselves, the reads may return garbage. Signed-off-by: Chris Wilson Cc: Tvrtko Ursulin Reviewed-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20180122100714.15137-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/intel_lrc.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index 51e61b0..22d471a 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -778,6 +778,7 @@ static void execlists_submission_tasklet(unsigned long data) struct intel_engine_execlists * const execlists = &engine->execlists; struct execlist_port * const port = execlists->port; struct drm_i915_private *dev_priv = engine->i915; + bool fw = false; /* We can skip acquiring intel_runtime_pm_get() here as it was taken * on our behalf by the request (see i915_gem_mark_busy()) and it will @@ -788,8 +789,6 @@ static void execlists_submission_tasklet(unsigned long data) */ GEM_BUG_ON(!dev_priv->gt.awake); - intel_uncore_forcewake_get(dev_priv, execlists->fw_domains); - /* 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). @@ -818,6 +817,12 @@ static void execlists_submission_tasklet(unsigned long data) */ __clear_bit(ENGINE_IRQ_EXECLIST, &engine->irq_posted); if (unlikely(execlists->csb_head == -1)) { /* following a reset */ + if (!fw) { + intel_uncore_forcewake_get(dev_priv, + execlists->fw_domains); + fw = true; + } + head = readl(dev_priv->regs + i915_mmio_reg_offset(RING_CONTEXT_STATUS_PTR(engine))); tail = GEN8_CSB_WRITE_PTR(head); head = GEN8_CSB_READ_PTR(head); @@ -830,10 +835,10 @@ static void execlists_submission_tasklet(unsigned long data) head = execlists->csb_head; tail = READ_ONCE(buf[write_idx]); } - GEM_TRACE("%s cs-irq head=%d [%d], tail=%d [%d]\n", + GEM_TRACE("%s cs-irq head=%d [%d%s], tail=%d [%d%s]\n", engine->name, - head, GEN8_CSB_READ_PTR(readl(dev_priv->regs + i915_mmio_reg_offset(RING_CONTEXT_STATUS_PTR(engine)))), - tail, GEN8_CSB_WRITE_PTR(readl(dev_priv->regs + i915_mmio_reg_offset(RING_CONTEXT_STATUS_PTR(engine))))); + head, GEN8_CSB_READ_PTR(readl(dev_priv->regs + i915_mmio_reg_offset(RING_CONTEXT_STATUS_PTR(engine)))), fw ? "" : "?", + tail, GEN8_CSB_WRITE_PTR(readl(dev_priv->regs + i915_mmio_reg_offset(RING_CONTEXT_STATUS_PTR(engine)))), fw ? "" : "?"); while (head != tail) { struct drm_i915_gem_request *rq; @@ -943,7 +948,8 @@ static void execlists_submission_tasklet(unsigned long data) if (!execlists_is_active(execlists, EXECLISTS_ACTIVE_PREEMPT)) execlists_dequeue(engine); - intel_uncore_forcewake_put(dev_priv, execlists->fw_domains); + if (fw) + intel_uncore_forcewake_put(dev_priv, execlists->fw_domains); } static void insert_request(struct intel_engine_cs *engine, -- 2.7.4