On 7/7/2015 5:50 PM, Sivakumar Thulasimani wrote:
On 7/7/2015 5:24 PM, Ville Syrjälä wrote:
On Tue, Jul 07, 2015 at 02:37:46PM +0300, Ville Syrjälä wrote:
On Tue, Jul 07, 2015 at 04:45:11PM +0530, Sivakumar Thulasimani wrote:
On 7/7/2015 4:40 PM, Ville Syrjälä wrote:
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.
No, the Compliance Sink tool, will not set the DP_DS_PORT_HPD
resulting
in detect not getting executed for
the short pulse generated. The spec requires the sink to set only the
sink count so it is not a must for
the sink to update the DP_DOWNSTREAM_PORT_0. so only a check for
SINK_COUNT will pass the
compliance test.
That seems stupid. If the downstream port isn't HPD capable then we
have
no reason to check SINK_COUNT after a short HPD as the short HPD
coudln't have been caused by a downstram HPD. Obviuously we still
check SINK_COUNT after a long HPD to figure out if anything is
connected
when the branch device itself gets connected to the source.
Actually that's not correct. We don't check SINK_COUNT unless the
downstream
port is HPD capable.
The spec says:
"If the DFP does not provide for means for plug/unplug detection, the
adaptor must set the SINK_COUNT field bits, as if those Sink devices
were
all permanently plugged."
So according to the there can't be any changes in SINK_COUNT if the
downstream port is not HPD capable.
yes, agree on the no changes for SINK_COUNT if HPD is 0. i'll check
with DP Compliance test
tomorrow and confirm the exact reason for its failure may be my
understanding of it was incorrect.
confirmed that the compliance sink is not setting HPD bit during detect.
so this looks to be a bug in
the sink tool. i'll file a bug with their team instead.
coming back to this patch, i will get back once i understand the complex
scenario of all short pulse
is treated as long pulse post this change, for example: we will do full
detection even if the sink requested
retraining of link.
--
regards,
Sivakumar
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