[Intel-gfx] [PATCH] [v2] drm/i915/bdw: Add 42ms delay for IPS disable

[Daniel Vetter]

On Thu, Apr 10, 2014 at 11:38:21PM +0000, Runyan, Arthur J wrote:
> Ben explained some of the fine details of the code to me, and I'm happy.
> Reviewed-by: Art Runyan <arthur.j.runyan at intel.com>
> 
> >
> >From: Ben Widawsky <benjamin.widawsky at linux.intel.com>
> >
> >This is a requirement added to the spec. This patch will prevent
> >persistent corruption on the display.
> >
> >v2: Make the wait before the vblank wait. (Art)
> >Try to finish early by polling the register
> >s/present/prevent (Chris)
> >
> >Cc: Art Runyan <arthur.j.runyan at intel.com>
> >Signed-off-by: Ben Widawsky <ben at bwidawsk.net>

Queued for -next, thanks for the patch.
> >---
> > drivers/gpu/drm/i915/intel_display.c | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> >diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> >index 7f02444..05c60b1 100644
> >--- a/drivers/gpu/drm/i915/intel_display.c
> >+++ b/drivers/gpu/drm/i915/intel_display.c
> >@@ -3583,10 +3583,13 @@ void hsw_disable_ips(struct intel_crtc *crtc)
> > 		return;
> >
> > 	assert_plane_enabled(dev_priv, crtc->plane);
> >-	if (IS_BROADWELL(crtc->base.dev)) {
> >+	if (IS_BROADWELL(dev)) {
> > 		mutex_lock(&dev_priv->rps.hw_lock);
> > 		WARN_ON(sandybridge_pcode_write(dev_priv, DISPLAY_IPS_CONTROL,
> >0));
> > 		mutex_unlock(&dev_priv->rps.hw_lock);
> >+		/* wait for pcode to finish disabling IPS, which may take up to 42ms */
> >+		if (wait_for((I915_READ(IPS_CTL) & IPS_ENABLE) == 0, 42))
> >+			DRM_DEBUG_KMS("Timed out waiting for IPS disable\n");

I've upgraded this to an ERROR to make sure we'll get noticed if it
happens.
-Daniel

> > 	} else {
> > 		I915_WRITE(IPS_CTL, 0);
> > 		POSTING_READ(IPS_CTL);
> >--
> >1.9.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch