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| author | Hans Verkuil <hverkuil@xs4all.nl> | 2018-05-15 03:21:01 -0400 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2018-05-25 15:34:50 -0400 |
| commit | 6aecad62670bb728d9616c672114d1627f877f33 (patch) | |
| tree | c561f8dabff479c0bb53d10be1624fde18a61708 /Documentation/media/uapi | |
| parent | df2b23861878f0128083f0d328ca2cfc6e721120 (diff) | |
| download | linux-6aecad62670bb728d9616c672114d1627f877f33.tar.gz linux-6aecad62670bb728d9616c672114d1627f877f33.tar.bz2 linux-6aecad62670bb728d9616c672114d1627f877f33.zip | |
media: cec: improve cec status documentation
Clarify the description of status bits, particularly w.r.t. ERROR and NACK.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans Verkuil <hansverk@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Diffstat (limited to 'Documentation/media/uapi')
| -rw-r--r-- | Documentation/media/uapi/cec/cec-ioc-receive.rst | 24 |
1 files changed, 15 insertions, 9 deletions
diff --git a/Documentation/media/uapi/cec/cec-ioc-receive.rst b/Documentation/media/uapi/cec/cec-ioc-receive.rst index bdad4b197bcd..e964074cd15b 100644 --- a/Documentation/media/uapi/cec/cec-ioc-receive.rst +++ b/Documentation/media/uapi/cec/cec-ioc-receive.rst @@ -231,26 +231,32 @@ View On' messages from initiator 0xf ('Unregistered') to destination 0 ('TV'). - ``CEC_TX_STATUS_OK`` - 0x01 - The message was transmitted successfully. This is mutually - exclusive with :ref:`CEC_TX_STATUS_MAX_RETRIES <CEC-TX-STATUS-MAX-RETRIES>`. Other bits can still - be set if earlier attempts met with failure before the transmit - was eventually successful. + exclusive with :ref:`CEC_TX_STATUS_MAX_RETRIES <CEC-TX-STATUS-MAX-RETRIES>`. + Other bits can still be set if earlier attempts met with failure before + the transmit was eventually successful. * .. _`CEC-TX-STATUS-ARB-LOST`: - ``CEC_TX_STATUS_ARB_LOST`` - 0x02 - - CEC line arbitration was lost. + - CEC line arbitration was lost, i.e. another transmit started at the + same time with a higher priority. Optional status, not all hardware + can detect this error condition. * .. _`CEC-TX-STATUS-NACK`: - ``CEC_TX_STATUS_NACK`` - 0x04 - - Message was not acknowledged. + - Message was not acknowledged. Note that some hardware cannot tell apart + a 'Not Acknowledged' status from other error conditions, i.e. the result + of a transmit is just OK or FAIL. In that case this status will be + returned when the transmit failed. * .. _`CEC-TX-STATUS-LOW-DRIVE`: - ``CEC_TX_STATUS_LOW_DRIVE`` - 0x08 - Low drive was detected on the CEC bus. This indicates that a follower detected an error on the bus and requests a - retransmission. + retransmission. Optional status, not all hardware can detect this + error condition. * .. _`CEC-TX-STATUS-ERROR`: - ``CEC_TX_STATUS_ERROR`` @@ -258,14 +264,14 @@ View On' messages from initiator 0xf ('Unregistered') to destination 0 ('TV'). - Some error occurred. This is used for any errors that do not fit ``CEC_TX_STATUS_ARB_LOST`` or ``CEC_TX_STATUS_LOW_DRIVE``, either because the hardware could not tell which error occurred, or because the hardware - tested for other conditions besides those two. + tested for other conditions besides those two. Optional status. * .. _`CEC-TX-STATUS-MAX-RETRIES`: - ``CEC_TX_STATUS_MAX_RETRIES`` - 0x20 - The transmit failed after one or more retries. This status bit is - mutually exclusive with :ref:`CEC_TX_STATUS_OK <CEC-TX-STATUS-OK>`. Other bits can still - be set to explain which failures were seen. + mutually exclusive with :ref:`CEC_TX_STATUS_OK <CEC-TX-STATUS-OK>`. + Other bits can still be set to explain which failures were seen. .. tabularcolumns:: |p{5.6cm}|p{0.9cm}|p{11.0cm}| |