[PATCH 3/4] drm/i915/hsw: Avoid early timeout during LCPLL disable/restore

Imre Deak
2016-06-28T10:37:40Z

Since wait_for_atomic doesn't re-check the wait-for condition after
expiry of the timeout it can fail when called from non-atomic context
even if the condition is set correctly before the expiry. Fix this by
using the non-atomic wait_for instead.

Fixes: 0351b93992aa ("drm/i915: Do not lie about atomic timeout granularity")
CC: Chris Wilson <chris@chris-wilson.co.uk>
CC: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
drivers/gpu/drm/i915/intel_display.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 0312472..d902a70 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -9534,8 +9534,8 @@ static void hsw_disable_lcpll(struct drm_i915_private *dev_priv,
val |= LCPLL_CD_SOURCE_FCLK;
I915_WRITE(LCPLL_CTL, val);

- if (wait_for_atomic_us(I915_READ(LCPLL_CTL) &
- LCPLL_CD_SOURCE_FCLK_DONE, 1))
+ if (wait_for_us(I915_READ(LCPLL_CTL) &
+ LCPLL_CD_SOURCE_FCLK_DONE, 1))
DRM_ERROR("Switching to FCLK failed\n");

val = I915_READ(LCPLL_CTL);
@@ -9608,8 +9608,8 @@ static void hsw_restore_lcpll(struct drm_i915_private *dev_priv)
val &= ~LCPLL_CD_SOURCE_FCLK;
I915_WRITE(LCPLL_CTL, val);

- if (wait_for_atomic_us((I915_READ(LCPLL_CTL) &
- LCPLL_CD_SOURCE_FCLK_DONE) == 0, 1))
+ if (wait_for_us((I915_READ(LCPLL_CTL) &
+ LCPLL_CD_SOURCE_FCLK_DONE) == 0, 1))
DRM_ERROR("Switching back to LCPLL failed\n");
}

--
2.5.0