media: cec: add xfer_timeout_ms field

Allow drivers to change the transmit timeout value, i.e. after how
long should a transmit be considered 'lost', i.e. the corresponding
cec_transmit_done_ts was never called.

Some CEC devices have their own timeout, and so this timeout value must be
longer than that hardware timeout value. If it is shorter then the
framework would consider the transmit lost, even though it is effectively
still in progress at the hardware level.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/cec/core/cec-adap.c

@@ -27,18 +27,6 @@ static void cec_fill_msg_report_features(struct cec_adapter *adap,
 					 struct cec_msg *msg,
 					 unsigned int la_idx);
 
-/*
- * 400 ms is the time it takes for one 16 byte message to be
- * transferred and 5 is the maximum number of retries. Add
- * another 100 ms as a margin. So if the transmit doesn't
- * finish before that time something is really wrong and we
- * have to time out.
- *
- * This is a sign that something it really wrong and a warning
- * will be issued.
- */
-#define CEC_XFER_TIMEOUT_MS (5 * 400 + 100)
-
 static int cec_log_addr2idx(const struct cec_adapter *adap, u8 log_addr)
 {
 	int i;
@@ -483,7 +471,7 @@ int cec_thread_func(void *_adap)
 				kthread_should_stop() ||
 				(!adap->transmit_in_progress &&
 				 !list_empty(&adap->transmit_queue)),
-				msecs_to_jiffies(CEC_XFER_TIMEOUT_MS));
+				msecs_to_jiffies(adap->xfer_timeout_ms));
 			timeout = err == 0;
 		} else {
 			/* Otherwise we just wait for something to happen. */
@@ -509,7 +497,8 @@ int cec_thread_func(void *_adap)
 			 * adapter driver, or the CEC bus is in some weird
 			 * state. On rare occasions it can happen if there is
 			 * so much traffic on the bus that the adapter was
-			 * unable to transmit for CEC_XFER_TIMEOUT_MS (2.1s).
+			 * unable to transmit for xfer_timeout_ms (2.1s by
+			 * default).
 			 */
 			if (adap->transmitting) {
 				pr_warn("cec-%s: message %*ph timed out\n", adap->name,

drivers/media/cec/core/cec-core.c

@@ -20,6 +20,18 @@
 #define CEC_NUM_DEVICES	256
 #define CEC_NAME	"cec"
 
+/*
+ * 400 ms is the time it takes for one 16 byte message to be
+ * transferred and 5 is the maximum number of retries. Add
+ * another 100 ms as a margin. So if the transmit doesn't
+ * finish before that time something is really wrong and we
+ * have to time out.
+ *
+ * This is a sign that something it really wrong and a warning
+ * will be issued.
+ */
+#define CEC_XFER_TIMEOUT_MS (5 * 400 + 100)
+
 int cec_debug;
 module_param_named(debug, cec_debug, int, 0644);
 MODULE_PARM_DESC(debug, "debug level (0-2)");
@@ -331,6 +343,8 @@ int cec_register_adapter(struct cec_adapter *adap,
 
 	adap->owner = parent->driver->owner;
 	adap->devnode.dev.parent = parent;
+	if (!adap->xfer_timeout_ms)
+		adap->xfer_timeout_ms = CEC_XFER_TIMEOUT_MS;
 
 #ifdef CONFIG_MEDIA_CEC_RC
 	if (adap->capabilities & CEC_CAP_RC) {

include/media/cec.h

@@ -168,6 +168,8 @@ struct cec_adap_ops {
  *			invalidated while the transmit is ongoing. In that
  *			case the transmit will finish, but will not retransmit
  *			and be marked as ABORTED.
+ * @xfer_timeout_ms:	the transfer timeout in ms.
+ *			If 0, then timeout after 2.1 ms.
  * @kthread_config:	kthread used to configure a CEC adapter
  * @config_completion:	used to signal completion of the config kthread
  * @kthread:		main CEC processing thread
@@ -224,6 +226,7 @@ struct cec_adapter {
 	struct cec_data *transmitting;
 	bool transmit_in_progress;
 	bool transmit_in_progress_aborted;
+	unsigned int xfer_timeout_ms;
 
 	struct task_struct *kthread_config;
 	struct completion config_completion;