On Mon, 2017-04-24 at 11:06 +0200, Jan Kiszka wrote: > On 2017-04-24 10:59, Andy Shevchenko wrote: > > On Sat, 2017-04-22 at 11:36 +0200, Jan Kiszka wrote: > > > From: Jan Kiszka <[email protected]> > > > > > > After migrating 8250_exar to MSI in 172c33cb61da, we can get stuck > > > without further interrupts because of the special wake-up event > > > these > > > chips send. They are only cleared by reading INT0. As we fail to > > > do so > > > during startup and shutdown, we can leave the interrupt line > > > asserted, > > > which is fatal with edge-triggered MSIs. > > > > > > Add the required reading of INT0 to startup and shutdown. Also > > > account > > > for the fact that a pending wake-up interrupt means we have to > > > return > > > 1 > > > from exar_handle_irq. > > > > > > An alternative approach would have been disabling the wake-up > > > interrupt. > > > Unfortunately, this feature (REGB[17] = 1) is not available on the > > > XR17D15X. > > > > > > Fixes: 172c33cb61da ("serial: exar: Enable MSI support") > > > Signed-off-by: Jan Kiszka <[email protected]> > > > --- > > > > > > Regression of upcoming 4.11. > > > > > > drivers/tty/serial/8250/8250_port.c | 19 ++++++++++--------- > > > 1 file changed, 10 insertions(+), 9 deletions(-) > > > > > > diff --git a/drivers/tty/serial/8250/8250_port.c > > > b/drivers/tty/serial/8250/8250_port.c > > > index 6119516ef5fc..3a3667880fcf 100644 > > > --- a/drivers/tty/serial/8250/8250_port.c > > > +++ b/drivers/tty/serial/8250/8250_port.c > > > @@ -47,6 +47,7 @@ > > > /* > > > * These are definitions for the Exar XR17V35X and XR17(C|D)15X > > > */ > > > +#define UART_EXAR_INT0 0x80 > > > #define UART_EXAR_SLEEP 0x8b /* Sleep mode > > > */ > > > #define UART_EXAR_DVID 0x8d /* Device > > > identification */ > > > > > > @@ -1869,17 +1870,13 @@ static int > > > serial8250_default_handle_irq(struct uart_port *port) > > > static int exar_handle_irq(struct uart_port *port) > > > { > > > unsigned int iir = serial_port_in(port, UART_IIR); > > > - int ret; > > > + int ret = 0; > > > > > > - ret = serial8250_handle_irq(port, iir); > > > + if (((port->type == PORT_XR17V35X) || (port->type == > > > PORT_XR17D15X)) && > > > + serial_port_in(port, UART_EXAR_INT0) != 0) > > > + ret = 1; > > > > > > - if ((port->type == PORT_XR17V35X) || > > > - (port->type == PORT_XR17D15X)) { > > > - serial_port_in(port, 0x80); > > > - serial_port_in(port, 0x81); > > > - serial_port_in(port, 0x82); > > > - serial_port_in(port, 0x83); > > > > You replaced 4 reads by one. I'm suspecting that on multi-port cards > > you > > still need to read all of them (I assume they are called INT0, INT1, > > ...). Perhaps you need a helper where you do that and call it from > > all > > necessary places. > > Nope, we never had to read them all: "Wake-up Indicator is cleared by > reading the INT0 register." (Exar manual) INT0 contains the interrupt > status for all channels.
Perhaps it needs to be mentioned in commit message as well. -- Andy Shevchenko <[email protected]> Intel Finland Oy
