On Wed, 26 Nov 2014, Paulo Zanoni <przanoni@xxxxxxxxx> wrote: > 2014-11-24 13:54 GMT-02:00 Daniel Vetter <daniel.vetter@xxxxxxxx>: >> Nothing in Bspec seems to indicate that we actually needs this, and it >> looks like can't work since by this point the pipe is off and so >> vblanks won't really happen any more. >> >> Note that Bspec mentions that it takes a vblank for this bit to >> change, but _only_ when enabling. >> >> Dropping this code quenches an annoying backtrace introduced by the >> more anal checking since >> >> commit 51e31d49c89055299e34b8f44d13f70e19aaaad1 >> Author: Daniel Vetter <daniel.vetter@xxxxxxxx> >> Date: Mon Sep 15 12:36:02 2014 +0200 >> >> drm/i915: Use generic vblank wait >> >> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=86095 >> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx> >> --- >> drivers/gpu/drm/i915/intel_dp.c | 17 +---------------- >> 1 file changed, 1 insertion(+), 16 deletions(-) >> >> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c >> index 46731da407c0..63fcdbf90652 100644 >> --- a/drivers/gpu/drm/i915/intel_dp.c >> +++ b/drivers/gpu/drm/i915/intel_dp.c >> @@ -3514,8 +3514,6 @@ intel_dp_link_down(struct intel_dp *intel_dp) >> enum port port = intel_dig_port->port; >> struct drm_device *dev = intel_dig_port->base.base.dev; >> struct drm_i915_private *dev_priv = dev->dev_private; >> - struct intel_crtc *intel_crtc = >> - to_intel_crtc(intel_dig_port->base.base.crtc); >> uint32_t DP = intel_dp->DP; >> >> if (WARN_ON(HAS_DDI(dev))) >> @@ -3540,8 +3538,6 @@ intel_dp_link_down(struct intel_dp *intel_dp) >> >> if (HAS_PCH_IBX(dev) && >> I915_READ(intel_dp->output_reg) & DP_PIPEB_SELECT) { >> - struct drm_crtc *crtc = intel_dig_port->base.base.crtc; >> - >> /* Hardware workaround: leaving our transcoder select >> * set to transcoder B while it's off will prevent the >> * corresponding HDMI output on transcoder A. >> @@ -3552,18 +3548,7 @@ intel_dp_link_down(struct intel_dp *intel_dp) >> */ >> DP &= ~DP_PIPEB_SELECT; >> I915_WRITE(intel_dp->output_reg, DP); >> - >> - /* Changes to enable or select take place the vblank >> - * after being written. >> - */ >> - if (WARN_ON(crtc == NULL)) { >> - /* We should never try to disable a port without a crtc >> - * attached. For paranoia keep the code around for a >> - * bit. */ >> - POSTING_READ(intel_dp->output_reg); >> - msleep(50); >> - } else >> - intel_wait_for_vblank(dev, intel_crtc->pipe); > > What I can guess is that we have the vblank wait here because the > DP_PORT_EN bit is still enabled at this point. It would make some > sense to have it if the pipe were not off... So removing the waits > looks sane: Reviewed-by: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx> > > But when I read the spec, it makes me think that maybe doing the > I915_WRITE above is also wrong, since the port is still enabled. Maybe > we should only clear bit 30 in the same write as the one that clears > bit 31? Ugh. So the spec says, "When disabling the port, software must temporarily enable the port with transcoder select (bit #30) cleared to ‘0’ after disabling the port." IIUC we should disable like we normally do, and do the w/a by enabling and disabling the port with DP_PIPEB_SELECT cleared *after* that. I think the current code is wrong, the patch is wrong, what Paulo suggests is wrong, and also intel_disable_hdmi() is wrong. BR, Jani. > > >> + POSTING_READ(intel_dp->output_reg); >> } >> >> DP &= ~DP_AUDIO_OUTPUT_ENABLE; >> -- >> 2.1.1 >> >> _______________________________________________ >> Intel-gfx mailing list >> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx >> http://lists.freedesktop.org/mailman/listinfo/intel-gfx > > > > -- > Paulo Zanoni > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > http://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx