Improve the internal CEC documentation. In particular add a section that specifies that
transmit-related interrupts should be processed before receive interrupts.
Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
---
diff --git a/Documentation/media/kapi/cec-core.rst b/Documentation/media/kapi/cec-core.rst
index 88c33b5..8a88dd4 100644
--- a/Documentation/media/kapi/cec-core.rst
+++ b/Documentation/media/kapi/cec-core.rst
@@ -106,13 +106,13 @@ your driver:
int (*adap_log_addr)(struct cec_adapter *adap, u8 logical_addr);
int (*adap_transmit)(struct cec_adapter *adap, u8 attempts,
u32 signal_free_time, struct cec_msg *msg);
- void (\*adap_log_status)(struct cec_adapter *adap);
+ void (*adap_status)(struct cec_adapter *adap, struct seq_file *file);
/* High-level callbacks */
...
};
-The three low-level ops deal with various aspects of controlling the CEC adapter
+The five low-level ops deal with various aspects of controlling the CEC adapter
hardware:
@@ -238,6 +238,18 @@ When a CEC message was received:
Speaks for itself.
+Implementing the interrupt handler
+----------------------------------
+
+Typically the CEC hardware provides interrupts that signal when a transmit
+finished and whether it was successful or not, and it provides and interrupt
+when a CEC message was received.
+
+The CEC driver should always process the transmit interrupts first before
+handling the receive interrupt. The framework expects to see the cec_transmit_done
+call before the cec_received_msg call, otherwise it can get confused if the
+received message was in reply to the transmitted message.
+
Implementing the High-Level CEC Adapter
---------------------------------------
@@ -247,11 +259,11 @@ CEC protocol driven. The following high-level callbacks are available:
.. code-block:: none
struct cec_adap_ops {
- /\* Low-level callbacks \*/
+ /* Low-level callbacks */
...
- /\* High-level CEC message callback \*/
- int (\*received)(struct cec_adapter \*adap, struct cec_msg \*msg);
+ /* High-level CEC message callback */
+ int (*received)(struct cec_adapter *adap, struct cec_msg *msg);
};
The received() callback allows the driver to optionally handle a newly
@@ -263,7 +275,7 @@ received CEC message
If the driver wants to process a CEC message, then it can implement this
callback. If it doesn't want to handle this message, then it should return
-ENOMSG, otherwise the CEC framework assumes it processed this message and
-it will not no anything with it.
+it will not do anything with it.
CEC framework functions
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