Em Fri, 17 Jun 2016 09:22:05 +0200 Hans Verkuil <hverkuil@xxxxxxxxx> escreveu: > On 06/16/2016 10:12 PM, Mauro Carvalho Chehab wrote: > > Em Fri, 29 Apr 2016 15:52:22 +0200 > > Hans Verkuil <hverkuil@xxxxxxxxx> escreveu: > > > >> From: Hans Verkuil <hansverk@xxxxxxxxx> > >> > >> Document the new HDMI CEC framework. > > > > As we'll be moving documentation to Sphinx/Rst, it would be good if > > you could make it work fine with sphinx, as this will likely be needed > > for Kernel 4.9. Right now it most works, although several warnings are > > produced: > > Would it be a problem if this conversion is done later in a separate patch? > > I'm all for it, but I don't have the time at the moment to do this. No problem. This can be done later. > > Regards, > > Hans > > > > > /devel/v4l/patchwork/tmp/cec.txt:40: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:40: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:40: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:40: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:40: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:42: WARNING: Definition list ends without a blank line; unexpected unindent. > > /devel/v4l/patchwork/tmp/cec.txt:42: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:67: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:71: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:92: ERROR: Unexpected indentation. > > /devel/v4l/patchwork/tmp/cec.txt:87: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:87: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:87: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:87: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:87: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:87: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:87: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:87: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:87: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:92: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:93: WARNING: Block quote ends without a blank line; 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unexpected unindent. > > /devel/v4l/patchwork/tmp/cec.txt:224: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:224: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:224: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:238: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:238: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:243: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:258: WARNING: Inline emphasis start-string without end-string. > > /devel/v4l/patchwork/tmp/cec.txt:258: WARNING: Inline emphasis start-string without end-string. > > > > > >> > >> Signed-off-by: Hans Verkuil <hansverk@xxxxxxxxx> > >> [k.debski@xxxxxxxxxxx: add DocBook documentation by Hans Verkuil, with > >> Signed-off-by: Kamil Debski <kamil@xxxxxxxxx> > >> Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx> > >> --- > >> Documentation/cec.txt | 267 ++++++++++++++++++++++++++++++++++++++++++++++++++ > >> 1 file changed, 267 insertions(+) > >> create mode 100644 Documentation/cec.txt > >> > >> diff --git a/Documentation/cec.txt b/Documentation/cec.txt > >> new file mode 100644 > >> index 0000000..75155fe > >> --- /dev/null > >> +++ b/Documentation/cec.txt > >> @@ -0,0 +1,267 @@ > >> +CEC Kernel Support > >> +================== > >> + > >> +The CEC framework provides a unified kernel interface for use with HDMI CEC > >> +hardware. It is designed to handle a multiple types of hardware (receivers, > >> +transmitters, USB dongles). The framework also gives the option to decide > >> +what to do in the kernel driver and what should be handled by userspace > >> +applications. In addition it integrates the remote control passthrough > >> +feature into the kernel's remote control framework. > >> + > >> + > >> +The CEC Protocol > >> +---------------- > >> + > >> +The CEC protocol enables consumer electronic devices to communicate with each > >> +other through the HDMI connection. The protocol uses logical addresses in the > >> +communication. The logical address is strictly connected with the functionality > >> +provided by the device. The TV acting as the communication hub is always > >> +assigned address 0. The physical address is determined by the physical > >> +connection between devices. > >> + > >> +The CEC framework described here is up to date with the CEC 2.0 specification. > >> +It is documented in the HDMI 1.4 specification with the new 2.0 bits documented > >> +in the HDMI 2.0 specification. But for most of the features the freely available > >> +HDMI 1.3a specification is sufficient: > >> + > >> +http://www.microprocessor.org/HDMISpecification13a.pdf > >> + > >> + > >> +The Kernel Interface > >> +==================== > >> + > >> +CEC Adapter > >> +----------- > >> + > >> +The struct cec_adapter represents the CEC adapter hardware. It is created by > >> +calling cec_allocate_adapter() and deleted by calling cec_delete_adapter(): > >> + > >> +struct cec_adapter *cec_allocate_adapter(const struct cec_adap_ops *ops, > >> + void *priv, const char *name, u32 caps, u8 available_las, > >> + struct device *parent); > >> +void cec_delete_adapter(struct cec_adapter *adap); > >> + > >> +To create an adapter you need to pass the following information: > >> + > >> +ops: adapter operations which are called by the CEC framework and that you > >> +have to implement. > >> + > >> +priv: will be stored in adap->priv and can be used by the adapter ops. > >> + > >> +name: the name of the CEC adapter. Note: this name will be copied. > >> + > >> +caps: capabilities of the CEC adapter. These capabilities determine the > >> + capabilities of the hardware and which parts are to be handled > >> + by userspace and which parts are handled by kernelspace. The > >> + capabilities are returned by CEC_ADAP_G_CAPS. > >> + > >> +available_las: the number of simultaneous logical addresses that this > >> + adapter can handle. Must be 1 <= available_las <= CEC_MAX_LOG_ADDRS. > >> + > >> +parent: the parent device. > >> + > >> + > >> +To register the /dev/cecX device node and the remote control device (if > >> +CEC_CAP_RC is set) you call: > >> + > >> +int cec_register_adapter(struct cec_adapter *adap); > >> + > >> +To unregister the devices call: > >> + > >> +void cec_unregister_adapter(struct cec_adapter *adap); > >> + > >> +Note: if cec_register_adapter() fails, then call cec_delete_adapter() to > >> +clean up. But if cec_register_adapter() succeeded, then only call > >> +cec_unregister_adapter() to clean up, never cec_delete_adapter(). The > >> +unregister function will delete the adapter automatically once the last user > >> +of that /dev/cecX device has closed its file handle. > >> + > >> + > >> +Implementing the Low-Level CEC Adapter > >> +-------------------------------------- > >> + > >> +The following low-level adapter operations have to be implemented in > >> +your driver: > >> + > >> +struct cec_adap_ops { > >> + /* Low-level callbacks */ > >> + int (*adap_enable)(struct cec_adapter *adap, bool enable); > >> + int (*adap_monitor_all_enable)(struct cec_adapter *adap, bool enable); > >> + 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); > >> + > >> + /* High-level callbacks */ > >> + ... > >> +}; > >> + > >> +The three low-level ops deal with various aspects of controlling the CEC adapter > >> +hardware: > >> + > >> + > >> +To enable/disable the hardware: > >> + > >> + int (*adap_enable)(struct cec_adapter *adap, bool enable); > >> + > >> +This callback enables or disables the CEC hardware. Enabling the CEC hardware > >> +means powering it up in a state where no logical addresses are claimed. This > >> +op assumes that the physical address (adap->phys_addr) is valid when enable is > >> +true and will not change while the CEC adapter remains enabled. The initial > >> +state of the CEC adapter after calling cec_allocate_adapter() is disabled. > >> + > >> +Note that adap_enable must return 0 if enable is false. > >> + > >> + > >> +To enable/disable the 'monitor all' mode: > >> + > >> + int (*adap_monitor_all_enable)(struct cec_adapter *adap, bool enable); > >> + > >> +If enabled, then the adapter should be put in a mode to also monitor messages > >> +that not for us. Not all hardware supports this and this function is only > >> +called if the CEC_CAP_MONITOR_ALL capability is set. This callback is optional > >> +(some hardware may always be in 'monitor all' mode). > >> + > >> +Note that adap_monitor_all_enable must return 0 if enable is false. > >> + > >> + > >> +To program a new logical address: > >> + > >> + int (*adap_log_addr)(struct cec_adapter *adap, u8 logical_addr); > >> + > >> +If logical_addr == CEC_LOG_ADDR_INVALID then all programmed logical addresses > >> +are to be erased. Otherwise the given logical address should be programmed. > >> +If the maximum number of available logical addresses is exceeded, then it > >> +should return -ENXIO. Once a logical address is programmed the CEC hardware > >> +can receive directed messages to that address. > >> + > >> +Note that adap_log_addr must return 0 if logical_addr is CEC_LOG_ADDR_INVALID. > >> + > >> + > >> +To transmit a new message: > >> + > >> + int (*adap_transmit)(struct cec_adapter *adap, u8 attempts, > >> + u32 signal_free_time, struct cec_msg *msg); > >> + > >> +This transmits a new message. The attempts argument is the suggested number of > >> +attempts for the transmit. > >> + > >> +The signal_free_time is the number of data bit periods that the adapter should > >> +wait when the line is free before attempting to send a message. This value > >> +depends on whether this transmit is a retry, a message from a new initiator or > >> +a new message for the same initiator. Most hardware will handle this > >> +automatically, but in some cases this information is needed. > >> + > >> +The CEC_FREE_TIME_TO_USEC macro can be used to convert signal_free_time to > >> +microseconds (one data bit period is 2.4 ms). > >> + > >> + > >> +To log the current CEC hardware status: > >> + > >> + void (*adap_status)(struct cec_adapter *adap, struct seq_file *file); > >> + > >> +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 > >> + > >> + > >> +Your adapter driver will also have to react to events (typically interrupt > >> +driven) by calling into the framework in the following situations: > >> + > >> +When a transmit finished (successfully or otherwise): > >> + > >> +void cec_transmit_done(struct cec_adapter *adap, u8 status, u8 arb_lost_cnt, > >> + u8 nack_cnt, u8 low_drive_cnt, u8 error_cnt); > >> + > >> +The status can be one of: > >> + > >> +CEC_TX_STATUS_OK: the transmit was successful. > >> +CEC_TX_STATUS_ARB_LOST: arbitration was lost: another CEC initiator > >> +took control of the CEC line and you lost the arbitration. > >> +CEC_TX_STATUS_NACK: the message was nacked (for a directed message) or > >> +acked (for a broadcast message). A retransmission is needed. > >> +CEC_TX_STATUS_LOW_DRIVE: low drive was detected on the CEC bus. This > >> +indicates that a follower detected an error on the bus and requested a > >> +retransmission. > >> +CEC_TX_STATUS_ERROR: some unspecified error occurred: this can be one of > >> +the previous two if the hardware cannot differentiate or something else > >> +entirely. > >> +CEC_TX_STATUS_MAX_RETRIES: could not transmit the message after > >> +trying multiple times. Should only be set by the driver if it has hardware > >> +support for retrying messages. If set, then the framework assumes that it > >> +doesn't have to make another attempt to transmit the message since the > >> +hardware did that already. > >> + > >> +The *_cnt arguments are the number of error conditions that were seen. > >> +This may be 0 if no information is available. Drivers that do not support > >> +hardware retry can just set the counter corresponding to the transmit error > >> +to 1, if the hardware does support retry then either set these counters to > >> +0 if the hardware provides no feedback of which errors occurred and how many > >> +times, or fill in the correct values as reported by the hardware. > >> + > >> +When a CEC message was received: > >> + > >> +void cec_received_msg(struct cec_adapter *adap, struct cec_msg *msg); > >> + > >> +Speaks for itself. > >> + > >> +Implementing the High-Level CEC Adapter > >> +--------------------------------------- > >> + > >> +The low-level operations drive the hardware, the high-level operations are > >> +CEC protocol driven. The following high-level callbacks are available: > >> + > >> +struct cec_adap_ops { > >> + /* Low-level callbacks */ > >> + ... > >> + > >> + /* 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 > >> +received CEC message > >> + > >> + int (*received)(struct cec_adapter *adap, struct cec_msg *msg); > >> + > >> +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. > >> + > >> + > >> +CEC framework functions > >> +----------------------- > >> + > >> +CEC Adapter drivers can call the following CEC framework functions: > >> + > >> +int cec_transmit_msg(struct cec_adapter *adap, struct cec_msg *msg, > >> + bool block); > >> + > >> +Transmit a CEC message. If block is true, then wait until the message has been > >> +transmitted, otherwise just queue it and return. > >> + > >> +void cec_s_phys_addr(struct cec_adapter *adap, u16 phys_addr, bool block); > >> + > >> +Change the physical address. This function will set adap->phys_addr and > >> +send an event if it has changed. If cec_s_log_addrs() has been called and > >> +the physical address has become valid, then the CEC framework will start > >> +claiming the logical addresses. If block is true, then this function won't > >> +return until this process has finished. > >> + > >> +When the physical address is set to a valid value the CEC adapter will > >> +be enabled (see the adap_enable op). When it is set to CEC_PHYS_ADDR_INVALID, > >> +then the CEC adapter will be disabled. If you change a valid physical address > >> +to another valid physical address, then this function will first set the > >> +address to CEC_PHYS_ADDR_INVALID before enabling the new physical address. > >> + > >> +int cec_s_log_addrs(struct cec_adapter *adap, > >> + struct cec_log_addrs *log_addrs, bool block); > >> + > >> +Claim the CEC logical addresses. Should never be called if CEC_CAP_LOG_ADDRS > >> +is set. If block is true, then wait until the logical addresses have been > >> +claimed, otherwise just queue it and return. To unconfigure all logical > >> +addresses call this function with log_addrs set to NULL or with > >> +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. > > > > > > > > Thanks, > > Mauro > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-media" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Thanks, Mauro -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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