Message ID | 20191211162954.8393-1-david.engraf@sysgo.com (mailing list archive) |
---|---|
State | Mainlined |
Commit | 751d0017334db9c4d68a8909c59f662a6ecbcec6 |
Headers | show |
Series | tty/serial: atmel: fix out of range clock divider handling | expand |
Hi, Le 11/12/2019 à 17:29, David Engraf a écrit : > Use MCK_DIV8 when the clock divider is > 65535. Unfortunately the mode > register was already written thus the clock selection is ignored. > > Fix by writing the mode register after calculating the baudrate. > > Signed-off-by: David Engraf <david.engraf@sysgo.com> It seems that this bug was introduced by: commit 5bf5635ac170 ("tty/serial: atmel: add fractional baud rate support") Could you add the "Fixes:" header ? Ludovic, could you check if this was your intent at the time ? > --- > drivers/tty/serial/atmel_serial.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c > index a8dc8af83f39..9983e2fabbac 100644 > --- a/drivers/tty/serial/atmel_serial.c > +++ b/drivers/tty/serial/atmel_serial.c > @@ -2270,9 +2270,6 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios, > mode |= ATMEL_US_USMODE_NORMAL; > } > I think it's better to mo move the "Set baud rate" block here (cf bellow) > - /* set the mode, clock divisor, parity, stop bits and data size */ > - atmel_uart_writel(port, ATMEL_US_MR, mode); > - > /* > * when switching the mode, set the RTS line state according to the > * new mode, otherwise keep the former state > @@ -2315,6 +2312,9 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios, > } > quot = cd | fp << ATMEL_US_FP_OFFSET; > > + /* set the mode, clock divisor, parity, stop bits and data size */ > + atmel_uart_writel(port, ATMEL_US_MR, mode); > + I think your patch is good, but I'll be happier if instead of moving those 2 lines here, the whole "Set the baud rate" block was moved before "atmel_uart_writel(port, ATMEL_US_MR, mode);" That's because at line 2291 the ATMEL_US_CR register is set with ATMEL_US_RTSDIS or ATMEL_US_RTSEN. And those 2 values have a different effect depending on US_MR.USART_MODE Quoting from the relase manual: RTSEN: 1: Drives RTS pin to 1 if US_MR.USART_MODE field = 2, else drives RTS pin to 0 if US_MR.USART_MODE field = 0. RTSDIS: 1: Drives RTS pin to 0 if US_MR.USART_MODE field = 2, else drives RTS pin to 1 if US_MR.USART_MODE field = 0. So, I think it's better to set the mode register before setting the control register. > if (!(port->iso7816.flags & SER_ISO7816_ENABLED)) > atmel_uart_writel(port, ATMEL_US_BRGR, quot); > atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX); > Thanks !
Hi, On 13.12.19 at 10:57, Richard Genoud wrote: > Hi, > > Le 11/12/2019 à 17:29, David Engraf a écrit : >> Use MCK_DIV8 when the clock divider is > 65535. Unfortunately the mode >> register was already written thus the clock selection is ignored. >> >> Fix by writing the mode register after calculating the baudrate. >> >> Signed-off-by: David Engraf <david.engraf@sysgo.com> > > It seems that this bug was introduced by: > commit 5bf5635ac170 ("tty/serial: atmel: add fractional baud rate support") > > Could you add the "Fixes:" header ? Sure. > Ludovic, could you check if this was your intent at the time ? > >> --- >> drivers/tty/serial/atmel_serial.c | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c >> index a8dc8af83f39..9983e2fabbac 100644 >> --- a/drivers/tty/serial/atmel_serial.c >> +++ b/drivers/tty/serial/atmel_serial.c >> @@ -2270,9 +2270,6 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios, >> mode |= ATMEL_US_USMODE_NORMAL; >> } >> > I think it's better to mo move the "Set baud rate" block here (cf bellow) > >> - /* set the mode, clock divisor, parity, stop bits and data size */ >> - atmel_uart_writel(port, ATMEL_US_MR, mode); >> - >> /* >> * when switching the mode, set the RTS line state according to the >> * new mode, otherwise keep the former state >> @@ -2315,6 +2312,9 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios, >> } >> quot = cd | fp << ATMEL_US_FP_OFFSET; >> >> + /* set the mode, clock divisor, parity, stop bits and data size */ >> + atmel_uart_writel(port, ATMEL_US_MR, mode); >> + > I think your patch is good, but I'll be happier if instead of moving > those 2 lines here, the whole "Set the baud rate" block was moved before > "atmel_uart_writel(port, ATMEL_US_MR, mode);" > > That's because at line 2291 the ATMEL_US_CR register is set with > ATMEL_US_RTSDIS or ATMEL_US_RTSEN. > And those 2 values have a different effect depending on US_MR.USART_MODE > > Quoting from the relase manual: > RTSEN: > 1: Drives RTS pin to 1 if US_MR.USART_MODE field = 2, else drives RTS > pin to 0 if US_MR.USART_MODE field = 0. > > RTSDIS: > 1: Drives RTS pin to 0 if US_MR.USART_MODE field = 2, else drives RTS > pin to 1 if US_MR.USART_MODE field = 0. > > So, I think it's better to set the mode register before setting the > control register. I fully agree, the RTS pin configuration depends on USART_MODE. I will make a new version of the patch. Thanks - David > >> if (!(port->iso7816.flags & SER_ISO7816_ENABLED)) >> atmel_uart_writel(port, ATMEL_US_BRGR, quot); >> atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX); >> > > Thanks ! >
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index a8dc8af83f39..9983e2fabbac 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -2270,9 +2270,6 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios, mode |= ATMEL_US_USMODE_NORMAL; } - /* set the mode, clock divisor, parity, stop bits and data size */ - atmel_uart_writel(port, ATMEL_US_MR, mode); - /* * when switching the mode, set the RTS line state according to the * new mode, otherwise keep the former state @@ -2315,6 +2312,9 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios, } quot = cd | fp << ATMEL_US_FP_OFFSET; + /* set the mode, clock divisor, parity, stop bits and data size */ + atmel_uart_writel(port, ATMEL_US_MR, mode); + if (!(port->iso7816.flags & SER_ISO7816_ENABLED)) atmel_uart_writel(port, ATMEL_US_BRGR, quot); atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);
Use MCK_DIV8 when the clock divider is > 65535. Unfortunately the mode register was already written thus the clock selection is ignored. Fix by writing the mode register after calculating the baudrate. Signed-off-by: David Engraf <david.engraf@sysgo.com> --- drivers/tty/serial/atmel_serial.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)