On Tue, Jul 07, 2015 at 03:26:36PM +0530, Sivakumar Thulasimani wrote:
>
>
> On 7/6/2015 5:42 PM, ville.syrjala@xxxxxxxxxxxxxxx wrote:
> > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> >
> > DP dongles may signal downstream HPD via short HPD pulses. If we know
> > the device has a HPD capable downstream port, make sure we kick off the
> > full hotplug processing even for short HPDs.
> >
> > Additonally setting the sink to DPMS off kills the downstream HPD (at
> > least on my DP->VGA dongle), so skip the DPMS off for such dongles
> > when we turn off the port.
> >
> > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/intel_dp.c | 18 +++++++++++++++++-
> > 1 file changed, 17 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> > index e88cec2..f424833 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -2324,6 +2324,13 @@ static void intel_dp_get_config(struct intel_encoder *encoder,
> > }
> > }
> >
> > +static bool intel_dp_has_downstream_hpd(struct intel_dp *intel_dp)
> > +{
> > + return intel_dp->dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT &&
> > + intel_dp->dpcd[DP_DPCD_REV] >= 0x11 &&
> > + intel_dp->downstream_ports[0] & DP_DS_PORT_HPD;
> > +}
> > +
> > static void intel_disable_dp(struct intel_encoder *encoder)
> > {
> > struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
> > @@ -2340,7 +2347,9 @@ static void intel_disable_dp(struct intel_encoder *encoder)
> > * ensure that we have vdd while we switch off the panel. */
> > intel_edp_panel_vdd_on(intel_dp);
> > intel_edp_backlight_off(intel_dp);
> > - intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
> > + /* Skip power down to keep downstream HPD working */
> > + if (!intel_dp_has_downstream_hpd(intel_dp))
> > + intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
> > intel_edp_panel_off(intel_dp);
> >
> > /* disable the port before the pipe on g4x */
> > @@ -4944,6 +4953,13 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
> > drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
> > intel_dp_check_link_status(intel_dp);
> > drm_modeset_unlock(&dev->mode_config.connection_mutex);
> > +
> > + /*
> > + * Downstream HPD will generate a short HPD,
> > + * so we want full hotplug processing here.
> > + */
> > + if (intel_dp_has_downstream_hpd(intel_dp))
> > + goto put_power;
> > }
> > }
> >
> I am looking into compliance changes for DP and this seems a relevant
> change for compliance as well. but as per Link CTS 1.2 section 4.2.2.8,
> we are supposed to read the sink_count and do full detection if
> sink_count is >1. So instead of checking for DP_DS_PORT_HPD can we just
> check SINK_COUNT and do full detect ?
->detect() will be called from the hotplug work and that will
check SINK_COUNT.
--
Ville Syrjälä
Intel OTC
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