| Message ID | 1347485049-19003-1-git-send-email-daniel.vetter@ffwll.ch (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Wed, 12 Sep 2012 23:24:09 +0200, Daniel Vetter <daniel.vetter@ffwll.ch> wrote: > It's bogus. > > If I've followed the history of this piece of code correctly, i.e. the > initial register write with the following vblank wait, this goes all > the way back to the original enabling of DP support in > > commit a4fc5ed69817c73e32571ad7837bb707f9890009 > Author: Keith Packard <keithp@keithp.com> > Date: Tue Apr 7 16:16:42 2009 -0700 > > drm/i915: Add Display Port support > > Unfortunately it seems to be nothing more than glorified duct-tape and > sometimes actively harmful. Adam Jackson noticed this for CPT > platforms with > > commit e85194641bec56179dcf5e1704ce5c6bf30340c6 > Author: Adam Jackson <ajax@redhat.com> > Date: Thu Jul 21 17:48:38 2011 -0400 > > drm/i915/dp: Don't turn CPT DP ports on too early > > Unfortunately this kept the code around for ilk and gm45. > > The specific failure case I'm seeing here is that after a dpms off/on > cycle we have the bits from the last link training (hopefully > successful link training) set in intel_dp->DP. This is requiered so > that complete_link_train can enable the port with the right tuning > values. > > Unfortunately writing these again to the disabled port at dpms on time > kills the port somehow until it's disabled - dp link training fails in > an endless loop without this patch on my mobile ilk and gm45. > > Cc: Chris Wilson <chris@chris-wilson.co.uk> > Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Works for me, only time will time if I no longer get the occasional failure in link training, but it definitely fixes the issue with dpms off. Tested-by: Chris Wilson <chris@chris-wilson.co.uk> Probably https://bugs.freedesktop.org/show_bug.cgi?id=51493 -Chris
On Thu, Sep 13, 2012 at 11:10:14AM +0100, Chris Wilson wrote: > On Wed, 12 Sep 2012 23:24:09 +0200, Daniel Vetter <daniel.vetter@ffwll.ch> wrote: > > It's bogus. > > > > If I've followed the history of this piece of code correctly, i.e. the > > initial register write with the following vblank wait, this goes all > > the way back to the original enabling of DP support in > > > > commit a4fc5ed69817c73e32571ad7837bb707f9890009 > > Author: Keith Packard <keithp@keithp.com> > > Date: Tue Apr 7 16:16:42 2009 -0700 > > > > drm/i915: Add Display Port support > > > > Unfortunately it seems to be nothing more than glorified duct-tape and > > sometimes actively harmful. Adam Jackson noticed this for CPT > > platforms with > > > > commit e85194641bec56179dcf5e1704ce5c6bf30340c6 > > Author: Adam Jackson <ajax@redhat.com> > > Date: Thu Jul 21 17:48:38 2011 -0400 > > > > drm/i915/dp: Don't turn CPT DP ports on too early > > > > Unfortunately this kept the code around for ilk and gm45. > > > > The specific failure case I'm seeing here is that after a dpms off/on > > cycle we have the bits from the last link training (hopefully > > successful link training) set in intel_dp->DP. This is requiered so > > that complete_link_train can enable the port with the right tuning > > values. > > > > Unfortunately writing these again to the disabled port at dpms on time > > kills the port somehow until it's disabled - dp link training fails in > > an endless loop without this patch on my mobile ilk and gm45. > > > > Cc: Chris Wilson <chris@chris-wilson.co.uk> > > Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch> > > Works for me, only time will time if I no longer get the occasional > failure in link training, but it definitely fixes the issue with dpms > off. > > Tested-by: Chris Wilson <chris@chris-wilson.co.uk> > Probably https://bugs.freedesktop.org/show_bug.cgi?id=51493 Queued for -next, thanks for testing - imo this patch is too risky for -fixes at this point in the release cycle. -Daniel
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 376ae28..3a4ebd4 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -1778,25 +1778,12 @@ static void intel_dp_start_link_train(struct intel_dp *intel_dp) { struct drm_device *dev = intel_dp->base.base.dev; - struct drm_i915_private *dev_priv = dev->dev_private; - struct intel_crtc *intel_crtc = to_intel_crtc(intel_dp->base.base.crtc); int i; uint8_t voltage; bool clock_recovery = false; int voltage_tries, loop_tries; uint32_t DP = intel_dp->DP; - /* - * On CPT we have to enable the port in training pattern 1, which - * will happen below in intel_dp_set_link_train. Otherwise, enable - * the port and wait for it to become active. - */ - if (!HAS_PCH_CPT(dev)) { - I915_WRITE(intel_dp->output_reg, intel_dp->DP); - POSTING_READ(intel_dp->output_reg); - intel_wait_for_vblank(dev, intel_crtc->pipe); - } - /* Write the link configuration data */ intel_dp_aux_native_write(intel_dp, DP_LINK_BW_SET, intel_dp->link_configuration,
It's bogus. If I've followed the history of this piece of code correctly, i.e. the initial register write with the following vblank wait, this goes all the way back to the original enabling of DP support in commit a4fc5ed69817c73e32571ad7837bb707f9890009 Author: Keith Packard <keithp@keithp.com> Date: Tue Apr 7 16:16:42 2009 -0700 drm/i915: Add Display Port support Unfortunately it seems to be nothing more than glorified duct-tape and sometimes actively harmful. Adam Jackson noticed this for CPT platforms with commit e85194641bec56179dcf5e1704ce5c6bf30340c6 Author: Adam Jackson <ajax@redhat.com> Date: Thu Jul 21 17:48:38 2011 -0400 drm/i915/dp: Don't turn CPT DP ports on too early Unfortunately this kept the code around for ilk and gm45. The specific failure case I'm seeing here is that after a dpms off/on cycle we have the bits from the last link training (hopefully successful link training) set in intel_dp->DP. This is requiered so that complete_link_train can enable the port with the right tuning values. Unfortunately writing these again to the disabled port at dpms on time kills the port somehow until it's disabled - dp link training fails in an endless loop without this patch on my mobile ilk and gm45. Cc: Chris Wilson <chris@chris-wilson.co.uk> Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch> --- drivers/gpu/drm/i915/intel_dp.c | 13 ------------- 1 file changed, 13 deletions(-)