On Wed, 31 May 2017, Ville Syrjälä <[email protected]> wrote: > On Wed, May 31, 2017 at 08:05:35PM +0300, Imre Deak wrote: >> Atm disabling either DP or eDP outputs can generate a spurious short >> pulse interrupt. The reason is that after disabling the port the source >> will stop sending a valid stream data, while the sink expects either a >> valid stream or the idle pattern. Since neither of this is sent the sink >> assumes (after an arbitrary delay) that the link is lost and requests >> for link retraining with a short pulse. >> >> The spurious pulse is a real problem at least for eDP panels with long >> power-off / power-cycle delays: as part of disabling the output we >> disable the panel power. The subsequent spurious short pulse handling >> will have to turn the power back on, which means the driver has to do a >> redundant wait for the power-off and power-cycle delays. During system >> suspend this leads to an unnecessary delay up to ~1s on systems with >> such panels as reported by Rui. >> >> To fix this put the sink to DPMS D3 state before turning off the port. >> According to the DP spec in this state the sink should not request >> retraining. This is also what we do already on pre-ddi platforms. >> >> As an alternative I also tried configuring the port to send idle pattern >> - which is against BSPec - and leave the port in normal mode before >> turning off the port. Neither of these resolved the problem. >> >> Cc: Zhang Rui <[email protected]> >> Cc: David Weinehall <[email protected]> >> Cc: Ville Syrjälä <[email protected]> >> Reported-and-tested-by: Zhang Rui <[email protected]> >> Signed-off-by: Imre Deak <[email protected]> > > Makes sense to me.
I wonder if we should write D0 on hotplug. BR, Jani. > > Reviewed-by: Ville Syrjälä <[email protected]> > >> --- >> drivers/gpu/drm/i915/intel_ddi.c | 10 +++++++--- >> 1 file changed, 7 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/gpu/drm/i915/intel_ddi.c >> b/drivers/gpu/drm/i915/intel_ddi.c >> index 0914ad9..8bac628 100644 >> --- a/drivers/gpu/drm/i915/intel_ddi.c >> +++ b/drivers/gpu/drm/i915/intel_ddi.c >> @@ -1732,12 +1732,18 @@ static void intel_ddi_post_disable(struct >> intel_encoder *intel_encoder, >> struct drm_i915_private *dev_priv = to_i915(encoder->dev); >> enum port port = intel_ddi_get_encoder_port(intel_encoder); >> struct intel_digital_port *dig_port = enc_to_dig_port(encoder); >> + struct intel_dp *intel_dp = NULL; >> int type = intel_encoder->type; >> uint32_t val; >> bool wait = false; >> >> /* old_crtc_state and old_conn_state are NULL when called from DP_MST */ >> >> + if (type == INTEL_OUTPUT_DP || type == INTEL_OUTPUT_EDP) { >> + intel_dp = enc_to_intel_dp(encoder); >> + intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF); >> + } >> + >> val = I915_READ(DDI_BUF_CTL(port)); >> if (val & DDI_BUF_CTL_ENABLE) { >> val &= ~DDI_BUF_CTL_ENABLE; >> @@ -1753,9 +1759,7 @@ static void intel_ddi_post_disable(struct >> intel_encoder *intel_encoder, >> if (wait) >> intel_wait_ddi_buf_idle(dev_priv, port); >> >> - if (type == INTEL_OUTPUT_DP || type == INTEL_OUTPUT_EDP) { >> - struct intel_dp *intel_dp = enc_to_intel_dp(encoder); >> - intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF); >> + if (intel_dp) { >> intel_edp_panel_vdd_on(intel_dp); >> intel_edp_panel_off(intel_dp); >> } >> -- >> 2.7.4 -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
