linux-kernel - [PATCH v2] drm: drm_probe_helper: Fix output_poll

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Date:   Wed, 31 Aug 2016 14:09:05 +0300
From:   Peter Ujfalusi <peter.ujfalusi@...com>
To:     <airlied@...ux.ie>, <daniel.vetter@...ll.ch>
CC:     <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        <ville.syrjala@...ux.intel.com>, <tomi.valkeinen@...com>
Subject: [PATCH v2] drm: drm_probe_helper: Fix output_poll_work scheduling

drm_kms_helper_poll_enable_locked() should check if we have delayed event
pending and if we have, schedule the work to run without delay.

Currently the output_poll_work is only scheduled if any of the connectors
have DRM_CONNECTOR_POLL_CONNECT or DRM_CONNECTOR_POLL_DISCONNECT with
DRM_OUTPUT_POLL_PERIOD delay. It does not matter if we have delayed event
already registered to be handled. The detection will be delayd by
DRM_OUTPUT_POLL_PERIOD in any case.
Furthermore if none of the connectors are marked as POLL_CONNECT or
POLL_DISCONNECT because all connectors are either POLL_HPD or they are
always connected: the output_poll_work will not run at all even if we
have delayed event marked.

When none of the connectors require polling, their initial status change
from unknown to connected/disconnected is not going to be handled until
the first kms application starts or if we have fb console enabled.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@...com>
---
Hi,

Changes since v1:
- dropped the last paragraph from the commit message.

Regards,
Peter

 drivers/gpu/drm/drm_probe_helper.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index a0df377d7d1c..f6b64d7d3528 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -129,6 +129,7 @@ void drm_kms_helper_poll_enable_locked(struct drm_device *dev)
 {
 	bool poll = false;
 	struct drm_connector *connector;
+	unsigned long delay = DRM_OUTPUT_POLL_PERIOD;

 	WARN_ON(!mutex_is_locked(&dev->mode_config.mutex));

@@ -141,8 +142,13 @@ void drm_kms_helper_poll_enable_locked(struct drm_device *dev)
 			poll = true;
 	}

+	if (dev->mode_config.delayed_event) {
+		poll = true;
+		delay = 0;
+	}
+
 	if (poll)
-		schedule_delayed_work(&dev->mode_config.output_poll_work, DRM_OUTPUT_POLL_PERIOD);
+		schedule_delayed_work(&dev->mode_config.output_poll_work, delay);
 }
 EXPORT_SYMBOL(drm_kms_helper_poll_enable_locked);

--
2.9.3