On 9/1/2015 4:12 PM, Jani Nikula wrote:
On Thu, 27 Aug 2015, Sivakumar Thulasimani <sivakumar.thulasimani@xxxxxxxxx> wrote:
From: "Thulasimani,Sivakumar" <sivakumar.thulasimani@xxxxxxxxx>
This patch checks for changes in sink count between short pulse
hpds and forces full detect when there is a change.
This will allow both detection of hotplug and unplug of panels
through dongles that give only short pulse for such events.
v2: changed variable type from u8 to bool (Jani)
return immediately if perform_full_detect is set(Siva)
The general idea LGTM, however see below.
Signed-off-by: Sivakumar Thulasimani <sivakumar.thulasimani@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_dp.c | 27 ++++++++++++++++++++++-----
1 file changed, 22 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 834f513..279e52c 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4370,26 +4370,39 @@ go_again:
* 4. Check link status on receipt of hot-plug interrupt
*/
static void
-intel_dp_check_link_status(struct intel_dp *intel_dp)
+intel_dp_check_link_status(struct intel_dp *intel_dp, bool *perform_full_detect)
{
struct drm_device *dev = intel_dp_to_dev(intel_dp);
struct intel_encoder *intel_encoder = &dp_to_dig_port(intel_dp)->base;
struct intel_crtc *crtc =
to_intel_crtc(dp_to_dig_port(intel_dp)->base.base.crtc);
u8 sink_irq_vector;
+ u8 old_sink_count = intel_dp->sink_count;
+ bool ret;
u8 link_status[DP_LINK_STATUS_SIZE];
WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
+ *perform_full_detect = false;
+
/* Try to read receiver status if the link appears to be up */
if (!intel_dp_get_link_status(intel_dp, link_status)) {
return;
}
- /* Now read the DPCD to see if it's actually running */
- if (!intel_dp_get_dpcd(intel_dp)) {
+ /* Now read the DPCD to see if it's actually running
+ * Don't return immediately if dpcd read failed,
+ * if sink count was 1 and dpcd read failed we need
+ * to do full detection
+ */
+ ret = intel_dp_get_dpcd(intel_dp);
+
+ if (old_sink_count != intel_dp->sink_count)
+ *perform_full_detect = true;
The point I was trying to make earlier is that how can you trust
intel_dp->sink_count if intel_dp_get_dpcd failed? You don't know where
it failed, and ->sink_count may or may not have changed. Maybe it has
changed for real but you didn't have a chance to read it just yet.
+
+ /* No need to proceed if we are going to do full detect */
+ if (!ret || *perform_full_detect)
return;
- }
So if you're returning because of !ret, *perform_full_detect may be true
or false, you don't know. I'd like the code to be explicit about what
you want the caller to do when intel_dp_get_dpcd returns false, full
detect or not.
BR,
Jani.
the idea i had in mind was if intel_dp_get_dpcd failed we should do a
full detect.
my assumption here was that sink_count would be zero so it would take care
of this, but now that it seems to be a wrong assumption how about the
following code ?
this makes it explicit that if dpcd read failed we will do full detect.
+ if ((old_sink_count != intel_dp->sink_count) || !ret)
+ *perform_full_detect = true;
+
+ /* No need to proceed if we are going to do full detect */
+ if (*perform_full_detect)
return;
if (!intel_encoder->base.crtc)
return;
@@ -5031,13 +5044,17 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
}
if (!intel_dp->is_mst) {
+ bool full_detect;
/*
* we'll check the link status via the normal hot plug path later -
* but for short hpds we should check it now
*/
drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
- intel_dp_check_link_status(intel_dp);
+ intel_dp_check_link_status(intel_dp, &full_detect);
drm_modeset_unlock(&dev->mode_config.connection_mutex);
+
+ if (full_detect)
+ goto put_power;
}
}
--
1.7.9.5
--
regards,
Sivakumar
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