> -----Original Message----- > From: Michael Walle <michael@xxxxxxxx> > Sent: 2022年11月23日 18:34 > To: Sherry Sun <sherry.sun@xxxxxxx> > Cc: gregkh@xxxxxxxxxxxxxxxxxxx; jirislaby@xxxxxxxxxx; > jingchang.lu@xxxxxxxxxxxxx; tomonori.sakita@xxxxxxxxxx; > atsushi.nemoto@xxxxxxxxxx; linux-serial@xxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx> > Subject: Re: [PATCH V2 2/5] tty: serial: fsl_lpuart: clear UARTCTRL_LOOPS in > lpuart32_shutdown() > > Am 2022-11-10 09:17, schrieb Sherry Sun: > > UARTCTRL_LOOPS bit is set in lpuart32_set_mctrl() for loopback mode, > > but nowhere clear this bit, it should be cleared when closing the uart > > port to avoid the loopback mode been enabled by default when reopening > > the uart. > > It's cleared in set_mctrl(). What is the expectation from the serial core here? > Hi Michael, If we call .set_mctrl(TIOCM_LOOP), the UARTCTRL_LOOPS will be set. Then when we call .shutdown(), serial core won't call .set_mctrl() to clear it, so the UARTCTRL_LOOPS need to be cleared here. Per my understanding, .shutdown() should clean up all the uart flags, as the transmitter and receiver will been disabled, we will re-configure all the settings needed when re-open the port. Best Regards Sherry
