drm/i915/lpt: Avoid early timeout during FDI PHY reset

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: 0351b939 ("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: NImre Deak <imre.deak@intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
CC: drm-intel-fixes@lists.freedesktop.org
Link: http://patchwork.freedesktop.org/patch/msgid/1467110253-16046-3-git-send-email-imre.deak@intel.com
(cherry picked from commit cf3598c2)
Signed-off-by: NJani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_display.c

@@ -8447,16 +8447,16 @@ 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");
 }