Re: [PATCH 2/2] tty: serial: fsl_lpuart: writing a 1 and then a 0 to trigger a break character
From: Michael Walle
Date: Fri Jul 15 2022 - 02:47:31 EST
Am 2022-07-15 04:59, schrieb Sherry Sun:
According to the lpuart reference manual, need to writing a 1 and then
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
I don't think this is correct. The tty core will already call this:
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.