[PATCH 06/25] drm/i915: Trim i915_do_reset() to minimum delays

Chris Wilson
2019-02-19T12:22:27Z

Remove the "safety-factor" in our udelays for i915_do_reset(). If we are
told to hold the line high for 20us, do it only for 20us plus the tiny
bit of udelay latency.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/i915_reset.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reset.c b/drivers/gpu/drm/i915/i915_reset.c
index 732f763a3999..358ab1d51570 100644
--- a/drivers/gpu/drm/i915/i915_reset.c
+++ b/drivers/gpu/drm/i915/i915_reset.c
@@ -167,12 +167,12 @@ static int i915_do_reset(struct drm_i915_private *i915,

/* Assert reset for at least 20 usec, and wait for acknowledgement. */
pci_write_config_byte(pdev, I915_GDRST, GRDOM_RESET_ENABLE);
- udelay(50);
+ udelay(20);
err = wait_for_atomic(i915_in_reset(pdev), 50);

/* Clear the reset request. */
pci_write_config_byte(pdev, I915_GDRST, 0);
- udelay(50);
+ udelay(20);
if (!err)
err = wait_for_atomic(!i915_in_reset(pdev), 50);