On Fri, Jul 3, 2020 at 1:32 PM Sergey Senozhatsky
<sergey.senozhat...@gmail.com> wrote:
>
> On (20/07/02 09:05), Tony Lindgren wrote:
> > * Sergey Senozhatsky <sergey.senozhat...@gmail.com> [200702 05:13]:
> > > On (20/06/30 11:02), Tony Lindgren wrote:
> > > > This conditional disable for irq_shared does not look nice to me
> > > > from the other device point of view :)
> > > >
> > > > Would it be possible to just set up te dummy interrupt handler
> > > > for the startup, then change it back afterwards? See for example
> > > > omap8250_no_handle_irq().
> > >
> > > I think we can do it. serial8250_do_startup() and irq handler take
> > > port->lock, so they should be synchronized.
> > >
> > > Something like this then?
> >
> > Yeah thanks this should work better for shared irq.
>
> This is, basically, an equivalent of
>
> ---
> drivers/tty/serial/8250/8250_port.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_port.c
> b/drivers/tty/serial/8250/8250_port.c
> index d64ca77d9cfa..dba7747d2ddd 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -2275,6 +2275,7 @@ int serial8250_do_startup(struct uart_port *port)
>
> if (port->irq && !(up->port.flags & UPF_NO_THRE_TEST)) {
> unsigned char iir1;
> +
> /*
> * Test for UARTs that do not reassert THRE when the
> * transmitter is idle and the interrupt has already
> @@ -2284,8 +2285,6 @@ int serial8250_do_startup(struct uart_port *port)
> * allow register changes to become visible.
> */
> spin_lock_irqsave(&port->lock, flags);
> - if (up->port.irqflags & IRQF_SHARED)
> - disable_irq_nosync(port->irq);
>
> wait_for_xmitr(up, UART_LSR_THRE);
> serial_port_out_sync(port, UART_IER, UART_IER_THRI);
> @@ -2297,8 +2296,6 @@ int serial8250_do_startup(struct uart_port *port)
> iir = serial_port_in(port, UART_IIR);
> serial_port_out(port, UART_IER, 0);
>
> - if (port->irqflags & IRQF_SHARED)
> - enable_irq(port->irq);
> spin_unlock_irqrestore(&port->lock, flags);
>
> /*
...which effectively is a revert of
768aec0b5bcc ("serial: 8250: fix shared interrupts issues with SMP and
RT kernels")
--
With Best Regards,
Andy Shevchenko
