[PATCH v2] media: cec-adap: add debounce support when setting an invalid phys addr

[Jonas Karlman <jonas@kwiboo.se>]

When EDID is refreshed, HDMI cable is unplugged/replugged or
an AVR is power cycled the CEC phys addr gets invalidated.

This can cause some disruption of CEC communication when
adapter is being reconfigured.

Add a debounce module option that can be used to debounce setting
an invalid phys addr. Default is not to use debouncing.

Using a configured debounce of e.g. 5000 ms, cec reconfiguring
could be avoided when AVR was power cycled on my setup.

Power off AVR (default cec.debounce=0):
[  101.536866] cec-dw_hdmi: new physical address f.f.f.f
[  102.495686] cec-dw_hdmi: new physical address 2.1.0.0
[  102.495913] cec-dw_hdmi: physical address: 2.1.0.0, claim 1 logical addresses
[  102.628574] cec-dw_hdmi: config: la 1 pa 2.1.0.0
[  105.130115] cec-dw_hdmi: new physical address f.f.f.f
[  106.979705] cec-dw_hdmi: new physical address 2.1.0.0
[  106.979872] cec-dw_hdmi: physical address: 2.1.0.0, claim 1 logical addresses
[  107.112399] cec-dw_hdmi: config: la 1 pa 2.1.0.0
[  108.979408] cec-dw_hdmi: reported physical address 2.0.0.0 for logical address 5
[  109.205386] cec-dw_hdmi: reported physical address 2.0.0.0 for logical address 11

Power on AVR (default cec.debounce=0):
[  158.398447] cec-dw_hdmi: new physical address f.f.f.f
[  161.977714] cec-dw_hdmi: new physical address 2.1.0.0
[  161.978766] cec-dw_hdmi: physical address: 2.1.0.0, claim 1 logical addresses
[  162.115624] cec-dw_hdmi: config: la 1 pa 2.1.0.0
[  162.402750] cec-dw_hdmi: new physical address f.f.f.f
[  162.403389] cec-dw_hdmi: cec_transmit_msg_fh: adapter is unconfigured
[  162.886757] cec-dw_hdmi: new physical address 2.1.0.0
[  162.886964] cec-dw_hdmi: physical address: 2.1.0.0, claim 1 logical addresses
[  163.510725] cec-dw_hdmi: config: la 1 pa 2.1.0.0
[  173.034200] cec-dw_hdmi: message 10 89 02 05 timed out

Power off AVR (cec.debounce=5000):
[  251.720471] cec-dw_hdmi: reported physical address 2.0.0.0 for logical address 5
[  251.922432] cec-dw_hdmi: reported physical address 2.0.0.0 for logical address 11

Power on AVR (cec.debounce=5000):
[  291.154262] cec-dw_hdmi: reported physical address 2.0.0.0 for logical address 5
[  291.296199] cec-dw_hdmi: reported physical address 2.0.0.0 for logical address 11

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
---
 drivers/media/cec/cec-adap.c |  9 ++++++++-
 drivers/media/cec/cec-core.c | 18 ++++++++++++++++++
 drivers/media/cec/cec-priv.h |  1 +
 include/media/cec.h          |  2 ++
 4 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/drivers/media/cec/cec-adap.c b/drivers/media/cec/cec-adap.c
index 5ef7daeb8cbd..4c94f6da526b 100644
--- a/drivers/media/cec/cec-adap.c
+++ b/drivers/media/cec/cec-adap.c
@@ -1593,8 +1593,15 @@ void cec_s_phys_addr(struct cec_adapter *adap, u16 phys_addr, bool block)
 	if (IS_ERR_OR_NULL(adap))
 		return;
 
+	cancel_delayed_work_sync(&adap->debounce_work);
+
 	mutex_lock(&adap->lock);
-	__cec_s_phys_addr(adap, phys_addr, block);
+	if (cec_debounce > 0 && !block && phys_addr == CEC_PHYS_ADDR_INVALID &&
+	    adap->phys_addr != phys_addr)
+		schedule_delayed_work(&adap->debounce_work,
+				      msecs_to_jiffies(cec_debounce));
+	else
+		__cec_s_phys_addr(adap, phys_addr, block);
 	mutex_unlock(&adap->lock);
 }
 EXPORT_SYMBOL_GPL(cec_s_phys_addr);
diff --git a/drivers/media/cec/cec-core.c b/drivers/media/cec/cec-core.c
index 9c610e1e99b8..fa93a724d7aa 100644
--- a/drivers/media/cec/cec-core.c
+++ b/drivers/media/cec/cec-core.c
@@ -28,6 +28,10 @@ static bool debug_phys_addr;
 module_param(debug_phys_addr, bool, 0644);
 MODULE_PARM_DESC(debug_phys_addr, "add CEC_CAP_PHYS_ADDR if set");
 
+int cec_debounce;
+module_param_named(debounce, cec_debounce, int, 0644);
+MODULE_PARM_DESC(debounce, "debounce invalid phys addr");
+
 static dev_t cec_dev_t;
 
 /* Active devices */
@@ -174,6 +178,8 @@ static void cec_devnode_unregister(struct cec_adapter *adap)
 	devnode->unregistered = true;
 	mutex_unlock(&devnode->lock);
 
+	cancel_delayed_work_sync(&adap->debounce_work);
+
 	mutex_lock(&adap->lock);
 	__cec_s_phys_addr(adap, CEC_PHYS_ADDR_INVALID, false);
 	__cec_s_log_addrs(adap, NULL, false);
@@ -250,6 +256,17 @@ static const struct file_operations cec_error_inj_fops = {
 };
 #endif
 
+static void cec_s_phys_addr_debounce(struct work_struct *work)
+{
+	struct delayed_work *delayed_work = to_delayed_work(work);
+	struct cec_adapter *adap =
+		container_of(delayed_work, struct cec_adapter, debounce_work);
+
+	mutex_lock(&adap->lock);
+	__cec_s_phys_addr(adap, CEC_PHYS_ADDR_INVALID, false);
+	mutex_unlock(&adap->lock);
+}
+
 struct cec_adapter *cec_allocate_adapter(const struct cec_adap_ops *ops,
 					 void *priv, const char *name, u32 caps,
 					 u8 available_las)
@@ -293,6 +310,7 @@ struct cec_adapter *cec_allocate_adapter(const struct cec_adap_ops *ops,
 	INIT_LIST_HEAD(&adap->transmit_queue);
 	INIT_LIST_HEAD(&adap->wait_queue);
 	init_waitqueue_head(&adap->kthread_waitq);
+	INIT_DELAYED_WORK(&adap->debounce_work, cec_s_phys_addr_debounce);
 
 	/* adap->devnode initialization */
 	INIT_LIST_HEAD(&adap->devnode.fhs);
diff --git a/drivers/media/cec/cec-priv.h b/drivers/media/cec/cec-priv.h
index 7bdf855aaecd..65176294fcf0 100644
--- a/drivers/media/cec/cec-priv.h
+++ b/drivers/media/cec/cec-priv.h
@@ -27,6 +27,7 @@ static inline bool msg_is_raw(const struct cec_msg *msg)
 
 /* cec-core.c */
 extern int cec_debug;
+extern int cec_debounce;
 int cec_get_device(struct cec_devnode *devnode);
 void cec_put_device(struct cec_devnode *devnode);
 
diff --git a/include/media/cec.h b/include/media/cec.h
index 4d59387bc61b..4d96ece01ba2 100644
--- a/include/media/cec.h
+++ b/include/media/cec.h
@@ -195,6 +195,8 @@ struct cec_adapter {
 	wait_queue_head_t kthread_waitq;
 	wait_queue_head_t waitq;
 
+	struct delayed_work debounce_work;
+
 	const struct cec_adap_ops *ops;
 	void *priv;
 	u32 capabilities;
-- 
2.17.1