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[RFC][PATCH 0/5 v3] adv7511 EDID probing improvements

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  [RFC][PATCH 0/5 v3] adv7511 EDID probing improvements John Stultz <john.stultz@linaro.org> - 2016-12-12 22:10 +0100
    [RFC][PATCH 1/5 v3] drm/bridge: adv7511: Use work_struct to defer hotplug handing to out of irq context John Stultz <john.stultz@linaro.org> - 2016-12-12 22:10 +0100

#1540663 — [RFC][PATCH 0/5 v3] adv7511 EDID probing improvements

Wanted to send out v3 of this patch set improving the EDID
probing on the adv7511 used on HiKey.

The first three patches are fixups that are hopefully straight
forward, integrating feedback I got from Laurant.

The last two patches try to clean up and resue code to avoid
an issue I'm seeing where something is going wrong with the
regmap cache state for the ADV7511_REG_EDID_I2C_ADDR (0x43)
register which results in i2c_transfer errors if we don't do the
regcache_sync/_mark_dirty() calls. I suspect there might be a
better solution there, so suggestions will be very welcome.

Thoughts and feedback would be appreciated!

thanks
-john

New in v3:
* Addressed naming improvements and drm_kms_helper_hotplug_event
  usage corrections as suggested by Laurent.

Cc: David Airlie <airlied@linux.ie>
Cc: Archit Taneja <architt@codeaurora.org>
Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: dri-devel@lists.freedesktop.org

Archit Taneja (1):
  drm/bridge: adv7511: Enable HPD interrupts to support hotplug and
    improve monitor detection

John Stultz (4):
  drm/bridge: adv7511: Use work_struct to defer hotplug handing to out
    of irq context
  drm/bridge: adv7511: Switch to using drm_kms_helper_hotplug_event()
  drm/bridge: adv7511: Rework adv7511_power_on/off() so they can be
    reused internally
  drm/bridge: adv7511: Reuse __adv7511_power_on/off() when probing EDID

 drivers/gpu/drm/bridge/adv7511/adv7511.h     |  2 +
 drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 62 +++++++++++++++++++---------
 2 files changed, 44 insertions(+), 20 deletions(-)

-- 
2.7.4

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#1540665 — [RFC][PATCH 1/5 v3] drm/bridge: adv7511: Use work_struct to defer hotplug handing to out of irq context

I was recently seeing issues with EDID probing, where
the logic to wait for the EDID read bit to be set by the
IRQ wasn't happening and the code would time out and fail.

Digging deeper, I found this was due to the fact that
IRQs were disabled as we were running in IRQ context from
the HPD signal.

Thus this patch changes the logic to handle the HPD signal
via a work_struct so we can be out of irq context.

With this patch, the EDID probing on hotplug does not time
out.

Cc: David Airlie <airlied@linux.ie>
Cc: Archit Taneja <architt@codeaurora.org>
Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
v3: Rename irq_work to hpd_work and remove extra whitespace, as
    suggested by Laurent
---
 drivers/gpu/drm/bridge/adv7511/adv7511.h     |  2 ++
 drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 11 ++++++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511.h b/drivers/gpu/drm/bridge/adv7511/adv7511.h
index 992d76c..0396791 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7511.h
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511.h
@@ -317,6 +317,8 @@ struct adv7511 {
 	bool edid_read;
 
 	wait_queue_head_t wq;
+	struct work_struct hpd_work;
+
 	struct drm_bridge bridge;
 	struct drm_connector connector;
 
diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
index 8dba729..4fcea44 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
@@ -402,6 +402,13 @@ static bool adv7511_hpd(struct adv7511 *adv7511)
 	return false;
 }
 
+static void adv7511_hpd_work(struct work_struct *work)
+{
+	struct adv7511 *adv7511 = container_of(work, struct adv7511, hpd_work);
+
+	drm_helper_hpd_irq_event(adv7511->connector.dev);
+}
+
 static int adv7511_irq_process(struct adv7511 *adv7511, bool process_hpd)
 {
 	unsigned int irq0, irq1;
@@ -419,7 +426,7 @@ static int adv7511_irq_process(struct adv7511 *adv7511, bool process_hpd)
 	regmap_write(adv7511->regmap, ADV7511_REG_INT(1), irq1);
 
 	if (process_hpd && irq0 & ADV7511_INT0_HPD && adv7511->bridge.encoder)
-		drm_helper_hpd_irq_event(adv7511->connector.dev);
+		schedule_work(&adv7511->hpd_work);
 
 	if (irq0 & ADV7511_INT0_EDID_READY || irq1 & ADV7511_INT1_DDC_ERROR) {
 		adv7511->edid_read = true;
@@ -1006,6 +1013,8 @@ static int adv7511_probe(struct i2c_client *i2c, const struct i2c_device_id *id)
 			goto err_i2c_unregister_edid;
 	}
 
+	INIT_WORK(&adv7511->hpd_work, adv7511_hpd_work);
+
 	if (i2c->irq) {
 		init_waitqueue_head(&adv7511->wq);
 
-- 
2.7.4

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