Re: [RFC PATCH] tty: serial: msm_serial: Don't reset uart on set_termios
On 06/13/2016 12:02 PM, Bjorn Andersson wrote: > Upon opening the tty, uart_open() ends up calling msm_set_baud_rate() > which resets the uart block. If this happens as we're coming out of > msm_console_write() a full fifo worth of console output will be > discarded. > > Cc: Stephen Boyd > Signed-off-by: Bjorn Andersson > --- > > As reported here: > https://bugs.96boards.org/show_bug.cgi?id=378 Urgh. As mentioned in commit a12f1b406f2d (tty: serial: msm: Reset uartdm after baud rate change, 2014-10-29) we actually need to reset the hardware sometimes. Perhaps as discussed over IRC we need to take a different approach here and only reset the hardware if the baud actually changes? One way to test this would be to try running a getty on the console and see if input still works. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
Re: [RFC PATCH] tty: serial: msm_serial: Don't reset uart on set_termios
On 14 June 2016 at 00:32, Bjorn Andersson wrote: > Upon opening the tty, uart_open() ends up calling msm_set_baud_rate() > which resets the uart block. If this happens as we're coming out of > msm_console_write() a full fifo worth of console output will be > discarded. > > Cc: Stephen Boyd > Signed-off-by: Bjorn Andersson > --- > > As reported here: > https://bugs.96boards.org/show_bug.cgi?id=378 > > drivers/tty/serial/msm_serial.c | 18 -- > 1 file changed, 18 deletions(-) Thanks for the patch. I no longer see these corruptions with this patch. This is what I used to see on my DB410C with debain FS: http://paste.ubuntu.com/17319106/ Tested-by: Pramod Gurav Regards, Pramod
[RFC PATCH] tty: serial: msm_serial: Don't reset uart on set_termios
Upon opening the tty, uart_open() ends up calling msm_set_baud_rate() which resets the uart block. If this happens as we're coming out of msm_console_write() a full fifo worth of console output will be discarded. Cc: Stephen Boyd Signed-off-by: Bjorn Andersson --- As reported here: https://bugs.96boards.org/show_bug.cgi?id=378 drivers/tty/serial/msm_serial.c | 18 -- 1 file changed, 18 deletions(-) diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c index b7d80bd57db9..93a10ac44933 100644 --- a/drivers/tty/serial/msm_serial.c +++ b/drivers/tty/serial/msm_serial.c @@ -813,23 +813,6 @@ static unsigned int msm_get_mctrl(struct uart_port *port) return TIOCM_CAR | TIOCM_CTS | TIOCM_DSR | TIOCM_RTS; } -static void msm_reset(struct uart_port *port) -{ - struct msm_port *msm_port = UART_TO_MSM(port); - - /* reset everything */ - msm_write(port, UART_CR_CMD_RESET_RX, UART_CR); - msm_write(port, UART_CR_CMD_RESET_TX, UART_CR); - msm_write(port, UART_CR_CMD_RESET_ERR, UART_CR); - msm_write(port, UART_CR_CMD_RESET_BREAK_INT, UART_CR); - msm_write(port, UART_CR_CMD_RESET_CTS, UART_CR); - msm_write(port, UART_CR_CMD_SET_RFR, UART_CR); - - /* Disable DM modes */ - if (msm_port->is_uartdm) - msm_write(port, 0, UARTDM_DMEN); -} - static void msm_set_mctrl(struct uart_port *port, unsigned int mctrl) { unsigned int mr; @@ -972,7 +955,6 @@ static int msm_set_baud_rate(struct uart_port *port, unsigned int baud, msm_write(port, 10, UART_TFWR); msm_write(port, UART_CR_CMD_PROTECTION_EN, UART_CR); - msm_reset(port); /* Enable RX and TX */ msm_write(port, UART_CR_TX_ENABLE | UART_CR_RX_ENABLE, UART_CR); -- 2.5.0