Messages in this thread | | | Date | Fri, 15 Jul 2022 08:47:00 +0200 | From | Michael Walle <> | Subject | Re: [PATCH 2/2] tty: serial: fsl_lpuart: writing a 1 and then a 0 to trigger a break character |
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Hi,
Am 2022-07-15 04:59, schrieb Sherry Sun: > According to the lpuart reference manual, need to writing a 1 and then > a > 0 to the UARTCTRL_SBK field queues a break character in the transmit > data stream. Only writing a 1 cannot trigger the break character, so > fix > it.
I don't think this is correct. The tty core will already call this: .break_ctl(port, 1) usleep() .break_ctl(port, 0)
So you'll have your 1->0 transition.
My RM from the LS1028A says the following:
| Writing a 1 and then a 0 to SBK queues a break character in the | transmit data stream. Additional break characters of 10 to 13, | or 13 to 16 if LPUART_STATBRK13] is set, bit times of logic 0 | are queued as long as SBK is set. Depending on the timing of | the set and clear of SBK relative to the information currently | being transmitted, a second break character may be queued | before software clears SBK.
To me it seems that setting the SBK bit just pulls the TX line low and releasing it will return to normal transmitter mode.
-michael
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