From a37951ac9f9642819e400814f6f30689db233c24 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Tue, 24 Jan 2017 11:00:06 +0000 Subject: [PATCH] drm/i915: Skip the execlists CSB scan and rewrite if the ring is untouched If the CSB head/tail pointers are unchanged, we can skip the update of the CSB register afterwards. Signed-off-by: Chris Wilson Reviewed-by: Joonas Lahtinen Link: http://patchwork.freedesktop.org/patch/msgid/20170124110009.28947-5-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/intel_lrc.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index f729568e5e54..99ab2d70be37 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -574,9 +574,12 @@ static void intel_lrc_irq_handler(unsigned long data) csb = readl(csb_mmio); head = GEN8_CSB_READ_PTR(csb); tail = GEN8_CSB_WRITE_PTR(csb); + if (head == tail) + break; + if (tail < head) tail += GEN8_CSB_ENTRIES; - while (head < tail) { + do { unsigned int idx = ++head % GEN8_CSB_ENTRIES; unsigned int status = readl(buf + 2 * idx); @@ -601,7 +604,7 @@ static void intel_lrc_irq_handler(unsigned long data) GEM_BUG_ON(port[0].count == 0 && !(status & GEN8_CTX_STATUS_ACTIVE_IDLE)); - } + } while (head < tail); writel(_MASKED_FIELD(GEN8_CSB_READ_PTR_MASK, GEN8_CSB_WRITE_PTR(csb) << 8), -- 2.20.1