Quoting Jorge Ramirez-Ortiz (2019-05-20 03:34:35) > When the tty layer requests the uart to throttle, the current code > executing in msm_serial will trigger "Bad mode in Error Handler" and > generate an invalid stack frame in pstore before rebooting (that is if > pstore is indeed configured: otherwise the user shall just notice a > reboot with no further information dumped to the console). > > This patch replaces the PIO byte accessor with the word accessor > already used in PIO mode. Because the hardware only accepts word based accessors and fails otherwise? I can believe that. I wonder if the earlier UART hardware this driver used to support (i.e. pre-DM) would accept byte access to the registers. It's possible, but we don't really care because those boards aren't supported. > > Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@xxxxxxxxxx> > --- Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx> > drivers/tty/serial/msm_serial.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c > index 109096033bb1..23833ad952ba 100644 > --- a/drivers/tty/serial/msm_serial.c > +++ b/drivers/tty/serial/msm_serial.c > @@ -869,10 +870,12 @@ static void msm_handle_tx(struct uart_port *port) > else > tf = port->membase + UART_TF; > > + buf[0] = port->x_char; > + > if (msm_port->is_uartdm) > msm_reset_dm_count(port, 1); > > - iowrite8_rep(tf, &port->x_char, 1); > + iowrite32_rep(tf, buf, 1); I suppose it's OK to write some extra zeroes here?
