Re: [PATCH 1/3] drm/i915: read sink_count dpcd always

[Sivakumar Thulasimani <sivakumar.thulasimani@xxxxxxxxx>]

On 8/26/2015 3:17 PM, Jani Nikula wrote:
> On Tue, 25 Aug 2015, Sivakumar Thulasimani <sivakumar.thulasimani@xxxxxxxxx> wrote:
> > From: "Thulasimani,Sivakumar" <sivakumar.thulasimani@xxxxxxxxx>
> >
> > This patch reads sink_count dpcd always and removes its
> > read operation based on values in downstream port dpcd. Also
> > we should read it irrespective of current status of sink.
> Having to write "also" in a commit message is a good hint to stop and
> think about whether that should be a separate patch. Maybe it should be,
> here too?
>
> BR,
> Jani.
:) i thought about it since that part of the message was added last, since
without those changes this patch will not be "read sink_count always".

will split it into two patches and rename them accordingly.
> > SINK_COUNT dpcd is not dependent on DOWNSTREAM_PORT_PRESENT dpcd.
> > SINK_COUNT denotes if a display is attached, while
> > DOWNSTREAM_PORT_PRESET indicates how many ports are available
> > in the dongle where display can be attached. so it is possible
> > for sink count to change irrespective of value in downstream
> > port dpcd.
> >
> > Here is a table of possible values and scenarios
> >
> > sink_count	downstream_port
> > 		present
> > 0		0		no display is attached
> > 0		1		dongle is connected without display
> > 1		0		display connected directly
> > 1		1		display connected through dongle
> >
> > Signed-off-by: Sivakumar Thulasimani <sivakumar.thulasimani@xxxxxxxxx>
> > ---
> >   drivers/gpu/drm/i915/intel_dp.c |   33 ++++++++++++++-------------------
> >   1 file changed, 14 insertions(+), 19 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> > index 8a66a44..9e4e27d 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -3898,6 +3898,7 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
> >   	struct drm_device *dev = dig_port->base.base.dev;
> >   	struct drm_i915_private *dev_priv = dev->dev_private;
> >   	uint8_t rev;
> > +	uint8_t reg;
> >   
> >   	if (intel_dp_dpcd_read_wake(&intel_dp->aux, 0x000, intel_dp->dpcd,
> >   				    sizeof(intel_dp->dpcd)) < 0)
> > @@ -3908,6 +3909,13 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
> >   	if (intel_dp->dpcd[DP_DPCD_REV] == 0)
> >   		return false; /* DPCD not present */
> >   
> > +	if (intel_dp_dpcd_read_wake(&intel_dp->aux, DP_SINK_COUNT,
> > +					    &reg, 1) < 0)
> > +			return false;
> > +
> > +	if (!DP_GET_SINK_COUNT(reg))
> > +		return false;
> > +
> >   	/* Check if the panel supports PSR */
> >   	memset(intel_dp->psr_dpcd, 0, sizeof(intel_dp->psr_dpcd));
> >   	if (is_edp(intel_dp)) {
> > @@ -4374,12 +4382,6 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
> >   
> >   	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
> >   
> > -	if (!intel_encoder->base.crtc)
> > -		return;
> > -
> > -	if (!to_intel_crtc(intel_encoder->base.crtc)->active)
> > -		return;
> > -
> >   	/* Try to read receiver status if the link appears to be up */
> >   	if (!intel_dp_get_link_status(intel_dp, link_status)) {
> >   		return;
> > @@ -4390,6 +4392,12 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
> >   		return;
> >   	}
> >   
> > +	if (!intel_encoder->base.crtc)
> > +		return;
> > +
> > +	if (!to_intel_crtc(intel_encoder->base.crtc)->active)
> > +		return;
> > +
> >   	/* Try to read the source of the interrupt */
> >   	if (intel_dp->dpcd[DP_DPCD_REV] >= 0x11 &&
> >   	    intel_dp_get_sink_irq(intel_dp, &sink_irq_vector)) {
> > @@ -4427,19 +4435,6 @@ intel_dp_detect_dpcd(struct intel_dp *intel_dp)
> >   	if (!(dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT))
> >   		return connector_status_connected;
> >   
> > -	/* If we're HPD-aware, SINK_COUNT changes dynamically */
> > -	if (intel_dp->dpcd[DP_DPCD_REV] >= 0x11 &&
> > -	    intel_dp->downstream_ports[0] & DP_DS_PORT_HPD) {
> > -		uint8_t reg;
> > -
> > -		if (intel_dp_dpcd_read_wake(&intel_dp->aux, DP_SINK_COUNT,
> > -					    &reg, 1) < 0)
> > -			return connector_status_unknown;
> > -
> > -		return DP_GET_SINK_COUNT(reg) ? connector_status_connected
> > -					      : connector_status_disconnected;
> > -	}
> > -
> >   	/* If no HPD, poke DDC gently */
> >   	if (drm_probe_ddc(&intel_dp->aux.ddc))
> >   		return connector_status_connected;
> > --
> > 1.7.9.5

--
regards,
Sivakumar

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