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Diffstat (limited to 'Documentation/DocBook/media/v4l/cec-ioc-receive.xml')
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diff --git a/Documentation/DocBook/media/v4l/cec-ioc-receive.xml b/Documentation/DocBook/media/v4l/cec-ioc-receive.xml new file mode 100644 index 000000000000..fde9f8678e67 --- /dev/null +++ b/Documentation/DocBook/media/v4l/cec-ioc-receive.xml @@ -0,0 +1,274 @@ +<refentry id="cec-ioc-receive"> + <refmeta> + <refentrytitle>ioctl CEC_RECEIVE, CEC_TRANSMIT</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>CEC_RECEIVE</refname> + <refname>CEC_TRANSMIT</refname> + <refpurpose>Receive or transmit a CEC message</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct cec_msg *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>File descriptor returned by + <link linkend='cec-func-open'><function>open()</function></link>.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>CEC_RECEIVE, CEC_TRANSMIT</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para> + Note: this documents the proposed CEC API. This API is not yet finalized and + is currently only available as a staging kernel module. + </para> + + <para>To receive a CEC message the application has to fill in the + <structname>cec_msg</structname> structure and pass it to the + <constant>CEC_RECEIVE</constant> ioctl. <constant>CEC_RECEIVE</constant> is + only available if <constant>CEC_CAP_RECEIVE</constant> is set. If the + file descriptor is in non-blocking mode and there are no received + messages pending, then it will return -1 and set errno to the &EAGAIN;. + If the file descriptor is in blocking mode and <structfield>timeout</structfield> + is non-zero and no message arrived within <structfield>timeout</structfield> + milliseconds, then it will return -1 and set errno to the &ETIMEDOUT;.</para> + + <para>To send a CEC message the application has to fill in the + <structname>cec_msg</structname> structure and pass it to the + <constant>CEC_TRANSMIT</constant> ioctl. <constant>CEC_TRANSMIT</constant> is + only available if <constant>CEC_CAP_TRANSMIT</constant> is set. + If there is no more room in the transmit queue, then it will return + -1 and set errno to the &EBUSY;.</para> + + <table pgwide="1" frame="none" id="cec-msg"> + <title>struct <structname>cec_msg</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u64</entry> + <entry><structfield>ts</structfield></entry> + <entry>Timestamp of when the message was transmitted in ns in the case + of <constant>CEC_TRANSMIT</constant> with <structfield>reply</structfield> + set to 0, or the timestamp of the received message in all other cases.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>len</structfield></entry> + <entry>The length of the message. For <constant>CEC_TRANSMIT</constant> this + is filled in by the application. The driver will fill this in for + <constant>CEC_RECEIVE</constant> and for <constant>CEC_TRANSMIT</constant> + it will be filled in with the length of the reply message if + <structfield>reply</structfield> was set.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>timeout</structfield></entry> + <entry>The timeout in milliseconds. This is the time the device will wait for a message to + be received before timing out. If it is set to 0, then it will wait indefinitely when it + is called by <constant>CEC_RECEIVE</constant>. If it is 0 and it is called by + <constant>CEC_TRANSMIT</constant>, then it will be replaced by 1000 if the + <structfield>reply</structfield> is non-zero or ignored if <structfield>reply</structfield> + is 0.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>sequence</structfield></entry> + <entry>The sequence number is automatically assigned by the CEC + framework for all transmitted messages. It can be later used by the + framework to generate an event if a reply for a message was + requested and the message was transmitted in a non-blocking mode. + </entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>flags</structfield></entry> + <entry>Flags. No flags are defined yet, so set this to 0.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>rx_status</structfield></entry> + <entry>The status bits of the received message. See <xref linkend="cec-rx-status" /> + for the possible status values. It is 0 if this message was transmitted, not + received, unless this is the reply to a transmitted message. In that case both + <structfield>rx_status</structfield> and <structfield>tx_status</structfield> + are set.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>tx_status</structfield></entry> + <entry>The status bits of the transmitted message. See <xref linkend="cec-tx-status" /> + for the possible status values. It is 0 if this messages was received, not + transmitted.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>msg</structfield>[16]</entry> + <entry>The message payload. For <constant>CEC_TRANSMIT</constant> this + is filled in by the application. The driver will fill this in for + <constant>CEC_RECEIVE</constant> and for <constant>CEC_TRANSMIT</constant> + it will be filled in with the payload of the reply message if + <structfield>reply</structfield> was set.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>reply</structfield></entry> + <entry>Wait until this message is replied. If <structfield>reply</structfield> + is 0 and the <structfield>timeout</structfield> is 0, then don't wait for a reply but + return after transmitting the message. If there was an error as indicated by a non-zero + <structfield>tx_status</structfield> field, then <structfield>reply</structfield> and + <structfield>timeout</structfield> are both set to 0 by the driver. Ignored by + <constant>CEC_RECEIVE</constant>. The case where <structfield>reply</structfield> is 0 + (this is the opcode for the Feature Abort message) and <structfield>timeout</structfield> + is non-zero is specifically allowed to send a message and wait up to <structfield>timeout</structfield> + milliseconds for a Feature Abort reply. In this case <structfield>rx_status</structfield> + will either be set to <constant>CEC_RX_STATUS_TIMEOUT</constant> or + <constant>CEC_RX_STATUS_FEATURE_ABORT</constant>.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>tx_arb_lost_cnt</structfield></entry> + <entry>A counter of the number of transmit attempts that resulted in the + Arbitration Lost error. This is only set if the hardware supports this, otherwise + it is always 0. This counter is only valid if the <constant>CEC_TX_STATUS_ARB_LOST</constant> + status bit is set.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>tx_nack_cnt</structfield></entry> + <entry>A counter of the number of transmit attempts that resulted in the + Not Acknowledged error. This is only set if the hardware supports this, otherwise + it is always 0. This counter is only valid if the <constant>CEC_TX_STATUS_NACK</constant> + status bit is set.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>tx_low_drive_cnt</structfield></entry> + <entry>A counter of the number of transmit attempts that resulted in the + Arbitration Lost error. This is only set if the hardware supports this, otherwise + it is always 0. This counter is only valid if the <constant>CEC_TX_STATUS_LOW_DRIVE</constant> + status bit is set.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>tx_error_cnt</structfield></entry> + <entry>A counter of the number of transmit errors other than Arbitration Lost + or Not Acknowledged. This is only set if the hardware supports this, otherwise + it is always 0. This counter is only valid if the <constant>CEC_TX_STATUS_ERROR</constant> + status bit is set.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="cec-tx-status"> + <title>CEC Transmit Status</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>CEC_TX_STATUS_OK</constant></entry> + <entry>0x01</entry> + <entry>The message was transmitted successfully. This is mutually exclusive with + <constant>CEC_TX_STATUS_MAX_RETRIES</constant>. Other bits can still be set if + earlier attempts met with failure before the transmit was eventually successful.</entry> + </row> + <row> + <entry><constant>CEC_TX_STATUS_ARB_LOST</constant></entry> + <entry>0x02</entry> + <entry>CEC line arbitration was lost.</entry> + </row> + <row> + <entry><constant>CEC_TX_STATUS_NACK</constant></entry> + <entry>0x04</entry> + <entry>Message was not acknowledged.</entry> + </row> + <row> + <entry><constant>CEC_TX_STATUS_LOW_DRIVE</constant></entry> + <entry>0x08</entry> + <entry>Low drive was detected on the CEC bus. This indicates that a follower + detected an error on the bus and requests a retransmission.</entry> + </row> + <row> + <entry><constant>CEC_TX_STATUS_ERROR</constant></entry> + <entry>0x10</entry> + <entry>Some error occurred. This is used for any errors that do not + fit the previous two, either because the hardware could not tell + which error occurred, or because the hardware tested for other conditions + besides those two.</entry> + </row> + <row> + <entry><constant>CEC_TX_STATUS_MAX_RETRIES</constant></entry> + <entry>0x20</entry> + <entry>The transmit failed after one or more retries. This status bit is mutually + exclusive with <constant>CEC_TX_STATUS_OK</constant>. Other bits can still be set + to explain which failures were seen.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="cec-rx-status"> + <title>CEC Receive Status</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>CEC_RX_STATUS_OK</constant></entry> + <entry>0x01</entry> + <entry>The message was received successfully.</entry> + </row> + <row> + <entry><constant>CEC_RX_STATUS_TIMEOUT</constant></entry> + <entry>0x02</entry> + <entry>The reply to an earlier transmitted message timed out.</entry> + </row> + <row> + <entry><constant>CEC_RX_STATUS_FEATURE_ABORT</constant></entry> + <entry>0x04</entry> + <entry>The message was received successfully but the reply was + <constant>CEC_MSG_FEATURE_ABORT</constant>. This status is only + set if this message was the reply to an earlier transmitted + message.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + </refsect1> +</refentry> |
