Messages in this thread | | | From | Stephen Boyd <> | Date | Fri, 22 Apr 2022 18:38:46 -0700 | Subject | Re: [PATCH v9 3/4] drm/msm/dp: wait for hpd high before aux transaction |
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Quoting Sankeerth Billakanti (2022-04-22 02:11:05) > The source device should ensure the sink is ready before proceeding to > read the sink capability or perform any aux transactions. The sink > will indicate its readiness by asserting the HPD line. The controller > driver needs to wait for the hpd line to be asserted by the sink before > it performs any aux transactions. > > The eDP sink is assumed to be always connected. It needs power from the > source and its HPD line will be asserted only after the panel is powered > on. The panel power will be enabled from the panel-edp driver and only > after that, the hpd line will be asserted. > > Whereas for DP, the sink can be hotplugged and unplugged anytime. The hpd > line gets asserted to indicate the sink is connected and ready. Hence > there is no need to wait for the hpd line to be asserted for a DP sink. > > Signed-off-by: Sankeerth Billakanti <quic_sbillaka@quicinc.com> > Reviewed-by: Douglas Anderson <dianders@chromium.org> > ---
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
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