From 00d70b15125030391d17baab2c2f70f93b3339a6 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 17 Mar 2011 07:18:29 +0000 Subject: [PATCH] drm/i915: skip redundant operations whilst enabling pipes and planes If the pipe or plane is already enabled, then we do not need to enable it again and can skip the delay. Similarly if it is already disabled when we want to disable it, we can also skip it. This fixes a regression from b24e717988, which caused the LVDS output on one PineView machine to become corrupt after changing orientation several times. References: https://bugs.freedesktop.org/show_bug.cgi?id=34601 Cc: Jesse Barnes Signed-off-by: Chris Wilson Reviewed-by: Keith Packard Tested-by: mengmeng.meng@intel.com --- drivers/gpu/drm/i915/intel_display.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 3bc6ab56cf8b..841f0397288b 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -1516,8 +1516,10 @@ static void intel_enable_pipe(struct drm_i915_private *dev_priv, enum pipe pipe, reg = PIPECONF(pipe); val = I915_READ(reg); - val |= PIPECONF_ENABLE; - I915_WRITE(reg, val); + if (val & PIPECONF_ENABLE) + return; + + I915_WRITE(reg, val | PIPECONF_ENABLE); intel_wait_for_vblank(dev_priv->dev, pipe); } @@ -1551,8 +1553,10 @@ static void intel_disable_pipe(struct drm_i915_private *dev_priv, reg = PIPECONF(pipe); val = I915_READ(reg); - val &= ~PIPECONF_ENABLE; - I915_WRITE(reg, val); + if ((val & PIPECONF_ENABLE) == 0) + return; + + I915_WRITE(reg, val & ~PIPECONF_ENABLE); intel_wait_for_pipe_off(dev_priv->dev, pipe); } @@ -1575,8 +1579,10 @@ static void intel_enable_plane(struct drm_i915_private *dev_priv, reg = DSPCNTR(plane); val = I915_READ(reg); - val |= DISPLAY_PLANE_ENABLE; - I915_WRITE(reg, val); + if (val & DISPLAY_PLANE_ENABLE) + return; + + I915_WRITE(reg, val | DISPLAY_PLANE_ENABLE); intel_wait_for_vblank(dev_priv->dev, pipe); } @@ -1607,8 +1613,10 @@ static void intel_disable_plane(struct drm_i915_private *dev_priv, reg = DSPCNTR(plane); val = I915_READ(reg); - val &= ~DISPLAY_PLANE_ENABLE; - I915_WRITE(reg, val); + if ((val & DISPLAY_PLANE_ENABLE) == 0) + return; + + I915_WRITE(reg, val & ~DISPLAY_PLANE_ENABLE); intel_flush_display_plane(dev_priv, plane); intel_wait_for_vblank(dev_priv->dev, pipe); } -- 2.39.2