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drm/i915: Skip the execlists CSB scan and rewrite if the ring is untouched

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If the CSB head/tail pointers are unchanged, we can skip the update of
the CSB register afterwards.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170124110009.28947-5-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2017-01-24 11:00:06 +00:00
parent f747026c2b
commit a37951ac9f
1 changed files with 5 additions and 2 deletions
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7
drivers/gpu/drm/i915/intel_lrc.c
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@ -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),