[media] pulse8-cec: add notes about behavior in autonomous mode

The pulse8 dongle has some quirky behaviors when in autonomous mode.
Document these.

Signed-off-by: Johan Fjeldtvedt <jaffe1@gmail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

diff --git a/drivers/staging/media/pulse8-cec/pulse8-cec.c b/drivers/staging/media/pulse8-cec/pulse8-cec.c
index dcda68a569a75ac99dc8aa47578d0dc29795341d..3361f4acfdafdfa3ebb7bccc6c0bb42f0c537a36 100644 (file)
--- a/drivers/staging/media/pulse8-cec/pulse8-cec.c
+++ b/drivers/staging/media/pulse8-cec/pulse8-cec.c
@@ -10,6 +10,29 @@
  * this archive for more details.
  */
 
+/*
+ * Notes:
+ *
+ * - Devices with firmware version < 2 do not store their configuration in
+ *   EEPROM.
+ *
+ * - In autonomous mode, only messages from a TV will be acknowledged, even
+ *   polling messages. Upon receiving a message from a TV, the dongle will
+ *   respond to messages from any logical address.
+ *
+ * - In autonomous mode, the dongle will by default reply Feature Abort
+ *   [Unrecognized Opcode] when it receives Give Device Vendor ID. It will
+ *   however observe vendor ID's reported by other devices and possibly
+ *   alter this behavior. When TV's (and TV's only) report that their vendor ID
+ *   is LG (0x00e091), the dongle will itself reply that it has the same vendor
+ *   ID, and it will respond to at least one vendor specific command.
+ *
+ * - In autonomous mode, the dongle is known to attempt wakeup if it receives
+ *   <User Control Pressed> ["Power On"], ["Power] or ["Power Toggle"], or if it
+ *   receives <Set Stream Path> with its own physical address. It also does this
+ *   if it receives <Vendor Specific Command> [0x03 0x00] from an LG TV.
+ */
+
 #include <linux/completion.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>