On 28/06/16 11:37, Imre Deak wrote:
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 <ch...@chris-wilson.co.uk>
CC: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
Signed-off-by: Imre Deak <imre.d...@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 c3b5dc8..0312472 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -8537,16 +8537,16 @@ static void lpt_reset_fdi_mphy(struct drm_i915_private 
*dev_priv)
        tmp |= FDI_MPHY_IOSFSB_RESET_CTL;
        I915_WRITE(SOUTH_CHICKEN2, tmp);

-       if (wait_for_atomic_us(I915_READ(SOUTH_CHICKEN2) &
-                              FDI_MPHY_IOSFSB_RESET_STATUS, 100))
+       if (wait_for_us(I915_READ(SOUTH_CHICKEN2) &
+                       FDI_MPHY_IOSFSB_RESET_STATUS, 100))
                DRM_ERROR("FDI mPHY reset assert timeout\n");

        tmp = I915_READ(SOUTH_CHICKEN2);
        tmp &= ~FDI_MPHY_IOSFSB_RESET_CTL;
        I915_WRITE(SOUTH_CHICKEN2, tmp);

-       if (wait_for_atomic_us((I915_READ(SOUTH_CHICKEN2) &
-                               FDI_MPHY_IOSFSB_RESET_STATUS) == 0, 100))
+       if (wait_for_us((I915_READ(SOUTH_CHICKEN2) &
+                        FDI_MPHY_IOSFSB_RESET_STATUS) == 0, 100))
                DRM_ERROR("FDI mPHY reset de-assert timeout\n");
  }

This one was easy to find non-atomic context is correct.

Reviewed-by: Tvrtko Ursulin <tvrtko.ursu...@intel.com>

Regards,

Tvrtko
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