diff options
Diffstat (limited to 'Documentation/media/kapi')
| -rw-r--r-- | Documentation/media/kapi/cec-core.rst | 40 | ||||
| -rw-r--r-- | Documentation/media/kapi/csi2.rst | 10 | ||||
| -rw-r--r-- | Documentation/media/kapi/v4l2-event.rst | 2 |
3 files changed, 52 insertions, 0 deletions
diff --git a/Documentation/media/kapi/cec-core.rst b/Documentation/media/kapi/cec-core.rst index 8a65c69ed071..28866259998c 100644 --- a/Documentation/media/kapi/cec-core.rst +++ b/Documentation/media/kapi/cec-core.rst @@ -107,6 +107,7 @@ your driver: int (*adap_transmit)(struct cec_adapter *adap, u8 attempts, u32 signal_free_time, struct cec_msg *msg); void (*adap_status)(struct cec_adapter *adap, struct seq_file *file); + void (*adap_free)(struct cec_adapter *adap); /* High-level callbacks */ ... @@ -184,6 +185,14 @@ To log the current CEC hardware status: This optional callback can be used to show the status of the CEC hardware. The status is available through debugfs: cat /sys/kernel/debug/cec/cecX/status +To free any resources when the adapter is deleted: + +.. c:function:: + void (*adap_free)(struct cec_adapter *adap); + +This optional callback can be used to free any resources that might have been +allocated by the driver. It's called from cec_delete_adapter. + Your adapter driver will also have to react to events (typically interrupt driven) by calling into the framework in the following situations: @@ -336,3 +345,34 @@ log_addrs->num_log_addrs set to 0. The block argument is ignored when unconfiguring. This function will just return if the physical address is invalid. Once the physical address becomes valid, then the framework will attempt to claim these logical addresses. + +CEC Pin framework +----------------- + +Most CEC hardware operates on full CEC messages where the software provides +the message and the hardware handles the low-level CEC protocol. But some +hardware only drives the CEC pin and software has to handle the low-level +CEC protocol. The CEC pin framework was created to handle such devices. + +Note that due to the close-to-realtime requirements it can never be guaranteed +to work 100%. This framework uses highres timers internally, but if a +timer goes off too late by more than 300 microseconds wrong results can +occur. In reality it appears to be fairly reliable. + +One advantage of this low-level implementation is that it can be used as +a cheap CEC analyser, especially if interrupts can be used to detect +CEC pin transitions from low to high or vice versa. + +.. kernel-doc:: include/media/cec-pin.h + +CEC Notifier framework +---------------------- + +Most drm HDMI implementations have an integrated CEC implementation and no +notifier support is needed. But some have independent CEC implementations +that have their own driver. This could be an IP block for an SoC or a +completely separate chip that deals with the CEC pin. For those cases a +drm driver can install a notifier and use the notifier to inform the +CEC driver about changes in the physical address. + +.. kernel-doc:: include/media/cec-notifier.h diff --git a/Documentation/media/kapi/csi2.rst b/Documentation/media/kapi/csi2.rst index e33fcb967922..0560100efca2 100644 --- a/Documentation/media/kapi/csi2.rst +++ b/Documentation/media/kapi/csi2.rst @@ -51,6 +51,16 @@ not active. Some transmitters do this automatically but some have to be explicitly programmed to do so, and some are unable to do so altogether due to hardware constraints. +Stopping the transmitter +^^^^^^^^^^^^^^^^^^^^^^^^ + +A transmitter stops sending the stream of images as a result of +calling the ``.s_stream()`` callback. Some transmitters may stop the +stream at a frame boundary whereas others stop immediately, +effectively leaving the current frame unfinished. The receiver driver +should not make assumptions either way, but function properly in both +cases. + Receiver drivers ---------------- diff --git a/Documentation/media/kapi/v4l2-event.rst b/Documentation/media/kapi/v4l2-event.rst index 9a5e31546ae3..9938d21ef4d1 100644 --- a/Documentation/media/kapi/v4l2-event.rst +++ b/Documentation/media/kapi/v4l2-event.rst @@ -67,6 +67,8 @@ type). The ops argument allows the driver to specify a number of callbacks: +.. tabularcolumns:: |p{1.5cm}|p{16.0cm}| + ======== ============================================================== Callback Description ======== ============================================================== |