From: Daniel Vetter Date: Tue, 30 Sep 2014 20:10:52 +0000 (+0200) Subject: drm/i915: Tighting frontbuffer tracking around flips X-Git-Tag: v6.6-pxa1908~22050^2~79^2~20 X-Git-Url: https://git.dujemihanovic.xyz/?a=commitdiff_plain;h=11c9b6c628c646894e6ef53f92cfd33a814ee553;p=linux.git drm/i915: Tighting frontbuffer tracking around flips So I think I've spotted a small gap in the frontbuffer tracking while discussing the logic with Paulo on irc: 1. Userspace schedules gpu rendering to the current frontbuffer. This gets tracked in dev_priv->fb_tracking.busy_bits. 2. We pageflip a fully rendered buffer before the frontbuffer rendering completes. 3. The request retiring will never clear busy_bits (since at retire time the old frontbuffer won't have obj->frontbuffer_bits set), so these bits now are stuck until someone again does a bit of frontbuffer tracking. If we clear stale busy_bits in flip_prepare this gap is closed. Reviewed-by: Paulo Zanoni Signed-off-by: Daniel Vetter --- diff --git a/drivers/gpu/drm/i915/intel_frontbuffer.c b/drivers/gpu/drm/i915/intel_frontbuffer.c index 7eb74a62117f..c5a312d218f7 100644 --- a/drivers/gpu/drm/i915/intel_frontbuffer.c +++ b/drivers/gpu/drm/i915/intel_frontbuffer.c @@ -248,8 +248,9 @@ void intel_frontbuffer_flip_prepare(struct drm_device *dev, struct drm_i915_private *dev_priv = dev->dev_private; mutex_lock(&dev_priv->fb_tracking.lock); - dev_priv->fb_tracking.flip_bits - |= frontbuffer_bits; + dev_priv->fb_tracking.flip_bits |= frontbuffer_bits; + /* Remove stale busy bits due to the old buffer. */ + dev_priv->fb_tracking.busy_bits &= ~frontbuffer_bits; mutex_unlock(&dev_priv->fb_tracking.lock); }