Lines Matching +full:cec +full:- +full:gpio
1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
5 CEC Pin Framework Error Injection
8 The CEC Pin Framework is a core CEC framework for CEC hardware that only
9 has low-level support for the CEC bus. Most hardware today will have
10 high-level CEC support where the hardware deals with driving the CEC bus,
12 allows you to connect the CEC pin to a GPIO on e.g. a Raspberry Pi and
13 you have now made a CEC adapter.
17 test how well CEC adapters can handle error conditions.
19 Currently only the cec-gpio driver (when the CEC line is directly
20 connected to a pull-up GPIO line) and the AllWinner A10/A20 drm driver
24 through debugfs. Specifically, in ``/sys/kernel/debug/cec/cecX/`` there is
25 now an ``error-inj`` file.
32 With ``cat error-inj`` you can see both the possible commands and the current
35 $ cat /sys/kernel/debug/cec/cec0/error-inj
38 # rx-clear clear all rx error injections
39 # tx-clear clear all tx error injections
41 # <op> rx-clear clear all rx error injections for <op>
42 # <op> tx-clear clear all tx error injections for <op>
45 # <op>[,<mode>] rx-nack NACK the message instead of sending an ACK
46 # <op>[,<mode>] rx-low-drive <bit> force a low-drive condition at this bit position
47 # <op>[,<mode>] rx-add-byte add a spurious byte to the received CEC message
48 # <op>[,<mode>] rx-remove-byte remove the last byte from the received CEC message
49 # any[,<mode>] rx-arb-lost [<poll>] generate a POLL message to trigger an arbitration lost
52 # tx-ignore-nack-until-eom ignore early NACKs until EOM
53 # tx-custom-low-usecs <usecs> define the 'low' time for the custom pulse
54 # tx-custom-high-usecs <usecs> define the 'high' time for the custom pulse
55 # tx-custom-pulse transmit the custom pulse once the bus is idle
58 # <op>[,<mode>] tx-no-eom don't set the EOM bit
59 # <op>[,<mode>] tx-early-eom set the EOM bit one byte too soon
60 # <op>[,<mode>] tx-add-bytes <num> append <num> (1-255) spurious bytes to the message
61 # <op>[,<mode>] tx-remove-byte drop the last byte from the message
62 # <op>[,<mode>] tx-short-bit <bit> make this bit shorter than allowed
63 # <op>[,<mode>] tx-long-bit <bit> make this bit longer than allowed
64 # <op>[,<mode>] tx-custom-bit <bit> send the custom pulse instead of this bit
65 # <op>[,<mode>] tx-short-start send a start pulse that's too short
66 # <op>[,<mode>] tx-long-start send a start pulse that's too long
67 # <op>[,<mode>] tx-custom-start send the custom pulse instead of the start pulse
68 # <op>[,<mode>] tx-last-bit <bit> stop sending after this bit
69 # <op>[,<mode>] tx-low-drive <bit> force a low-drive condition at this bit position
71 # <op> CEC message opcode (0-255) or 'any'
73 # <bit> CEC message bit (0-159)
74 # 10 bits per 'byte': bits 0-7: data, bit 8: EOM, bit 9: ACK
75 # <poll> CEC poll message used to test arbitration lost (0x00-0xff, default 0x0f)
76 # <usecs> microseconds (0-10000000, default 1000)
80 You can write error injection commands to ``error-inj`` using
81 ``echo 'cmd' >error-inj`` or ``cat cmd.txt >error-inj``. The ``cat error-inj``
83 and use it as an input to ``error-inj`` later.
86 ------------
93 receiving CEC messages and those relating to transmitting CEC messages. In
95 to create custom pulses on the CEC bus.
97 Most error injection commands can be executed for specific CEC opcodes or for
105 So '``any rx-nack``' will NACK the next received CEC message,
106 '``any,always rx-nack``' will NACK all received CEC messages and
107 '``0x82,toggle rx-nack``' will only NACK if an Active Source message was
111 is cleared automatically, so ``once`` is a one-time deal.
113 All combinations of ``<op>`` and error injection commands can co-exist. So
116 0x9e tx-add-bytes 1
117 0x9e tx-early-eom
118 0x9f tx-add-bytes 2
119 any rx-nack
126 0x9e tx-add-bytes 1
127 0x9e tx-add-bytes 2
132 ----------------------
137 ``rx-clear``
140 ``tx-clear``
146 ``<op> rx-clear``
149 ``<op> tx-clear``
153 ----------------
155 ``<op>[,<mode>] rx-nack``
156 NACK broadcast messages and messages directed to this CEC adapter.
160 ``<op>[,<mode>] rx-low-drive <bit>``
162 a specific CEC opcode then the bit position must be at least 18,
169 ``<op>[,<mode>] rx-add-byte``
170 Add a spurious 0x55 byte to the received CEC message, provided
172 the high-level protocol since spurious bytes should be ignored.
174 ``<op>[,<mode>] rx-remove-byte``
175 Remove the last byte from the received CEC message, provided it
176 was at least 2 bytes long. This is useful to test the high-level
179 ``<op>[,<mode>] rx-arb-lost <poll>``
182 As soon as a start bit has been received the CEC adapter will switch
187 the remote CEC transmitter. Arbitration happens when two CEC adapters
193 This does not work if the remote CEC transmitter has logical address
197 -----------------
199 ``tx-ignore-nack-until-eom``
200 This setting changes the behavior of transmitting CEC messages. Normally
204 recommended behavior since there is no point in keeping the CEC bus busy
210 ``<op>[,<mode>] tx-no-eom``
212 (End-Of-Message) bit set. With this command the transmit will just stop
214 handles this case. Normally receivers have a time-out after which
217 ``<op>[,<mode>] tx-early-eom``
219 of two bytes or more. The EOM bit will be set for the second-to-last byte
225 ``<op>[,<mode>] tx-add-bytes <num>``
226 Append ``<num>`` (1-255) spurious bytes to the message. The extra bytes
228 two byte message (e.g. a Get CEC Version message) and add 2 bytes, then
229 the full message received by the remote CEC adapter is
236 ``<op>[,<mode>] tx-remove-byte``
240 ``<op>[,<mode>] tx-short-bit <bit>``
242 an Ack bit. If <op> specifies a specific CEC opcode then the bit position
246 done by reducing the time the CEC bus is high. This bit period is less
253 sees a too-short 0 bit.
255 ``<op>[,<mode>] tx-long-bit <bit>``
257 an Ack bit. If <op> specifies a specific CEC opcode then the bit position
261 done by increasing the time the CEC bus is high.
265 return to Idle state. Unfortunately the CEC specification is silent about
271 sees a too-long 0 bit.
273 ``<op>[,<mode>] tx-short-start``
277 the time the CEC bus is high. This start bit period is less than is
280 ``<op>[,<mode>] tx-long-start``
284 the time the CEC bus is high. This start bit period is more than is
289 return to Idle state. Unfortunately the CEC specification is silent about
292 ``<op>[,<mode>] tx-last-bit <bit>``
293 Just stop transmitting after this bit. If <op> specifies a specific CEC
299 ``<op>[,<mode>] tx-low-drive <bit>``
301 specific CEC opcode then the bit position must be at least 18, otherwise
304 positions 0-3 the receiver can interpret this as an Arbitration Lost
308 -------------
310 ``tx-custom-low-usecs <usecs>``
312 the CEC line low. The default is 1000 microseconds.
314 ``tx-custom-high-usecs <usecs>``
316 CEC line high (unless another CEC adapter pulls it low in that time).
318 ``tx-custom-low-usecs + tx-custom-high-usecs``.
320 ``<op>[,<mode>] tx-custom-bit <bit>``
322 be an Ack bit. If <op> specifies a specific CEC opcode then the bit
325 ``<op>[,<mode>] tx-custom-start``
328 ``tx-custom-pulse``
329 Transmit a single custom pulse as soon as the CEC bus is idle.