From: Daniel Vetter Date: Tue, 22 May 2012 19:41:25 +0000 (+0200) Subject: drm/i915: wait for a vblank to pass after tv detect X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=bf2125e2f7e931b50a6c76ba0435ba001409ccbf;p=deliverable%2Flinux.git drm/i915: wait for a vblank to pass after tv detect Otherwise the hw will get confused and result in a black screen. This regression has been most likely introduce in commit 974b93315b2213b74a42a87e8a9d4fc8c0dbe90c Author: Chris Wilson Date: Sun Sep 5 00:44:20 2010 +0100 drm/i915/tv: Poll for DAC state change That commit replace the first msleep(20) with a busy-loop, but failed to keep the 2nd msleep around. Later on we've replaced all these msleep(20) by proper vblanks. For reference also see the commit in xf86-video-intel: commit 1142be53eb8d2ee8a9b60ace5d49f0ba27332275 Author: Jesse Barnes Date: Mon Jun 9 08:52:59 2008 -0700 Fix TV programming: add vblank wait after TV_CTL writes Fxies FDO bug #14000; we need to wait for vblank after writing TV_CTL or following "DPMS on" calls may not actually enable the output. v2: As suggested by Chris Wilson, add a small comment to ensure that no one accidentally removes this vblank wait again - there really seems to be no sane explanation for why we need it, but it is required. Launchpad: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/763688 Reported-and-Tested-by: Robert Lowery Cc: Rodrigo Vivi Cc: stable@vger.kernel.org Acked-by: Chris Wilson Signed-Off-by: Daniel Vetter --- diff --git a/drivers/gpu/drm/i915/intel_tv.c b/drivers/gpu/drm/i915/intel_tv.c index 3346612d2953..475f6d4d97fd 100644 --- a/drivers/gpu/drm/i915/intel_tv.c +++ b/drivers/gpu/drm/i915/intel_tv.c @@ -1194,6 +1194,11 @@ intel_tv_detect_type(struct intel_tv *intel_tv, I915_WRITE(TV_DAC, save_tv_dac & ~TVDAC_STATE_CHG_EN); I915_WRITE(TV_CTL, save_tv_ctl); + POSTING_READ(TV_CTL); + + /* For unknown reasons the hw barfs if we don't do this vblank wait. */ + intel_wait_for_vblank(intel_tv->base.base.dev, + to_intel_crtc(intel_tv->base.base.crtc)->pipe); /* Restore interrupt config */ if (connector->polled & DRM_CONNECTOR_POLL_HPD) {