On Thu, Nov 10, 2022 at 01:09:59AM +0000, Joel Stanley wrote:
> On Mon, 7 Nov 2022 at 17:15, Gabriel Somlo <gsomlo@xxxxxxxxx> wrote:
> >
> > Move the character-receive (RX) loop to its own dedicated function,
> > and (for now) call that from the poll timer, liteuart_timer().
> >
> > This is in preparation for adding IRQ support to the receive path.
> >
> > Signed-off-by: Gabriel Somlo <gsomlo@xxxxxxxxx>
> > ---
> > drivers/tty/serial/liteuart.c | 25 +++++++++++++++----------
> > 1 file changed, 15 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/tty/serial/liteuart.c b/drivers/tty/serial/liteuart.c
> > index 4b9cca249828..90a29ed79bff 100644
> > --- a/drivers/tty/serial/liteuart.c
> > +++ b/drivers/tty/serial/liteuart.c
> > @@ -69,29 +69,34 @@ static struct uart_driver liteuart_driver = {
> > #endif
> > };
> >
> > -static void liteuart_timer(struct timer_list *t)
> > +static void liteuart_rx_chars(struct uart_port *port)
> > {
> > - struct liteuart_port *uart = from_timer(uart, t, timer);
> > - struct uart_port *port = &uart->port;
> > unsigned char __iomem *membase = port->membase;
> > - unsigned int flg = TTY_NORMAL;
> > - int ch;
> > - unsigned long status;
> > + unsigned int status;
> > + unsigned char ch;
>
> u32, u8, void __iomem * would be better kernel types to use here.
>
> You've also changed ch from a signed 32 to an unsigned 8.
uart_insert_char() expects both `status` and `ch` to be of type
`unsigned int`. Switching `ch` to 8-bit was a typo, thanks for
catching it!
I'm going to use `unsigned int status, ch` in v3, to match the
signature of `uart_insert_char()` -- hope that's OK. This will be
a separate commit preceding the "move rx loop out of poll timer"
change.
> >
> > while ((status = !litex_read8(membase + OFF_RXEMPTY)) == 1) {
> > ch = litex_read8(membase + OFF_RXTX);
> > port->icount.rx++;
> >
> > /* necessary for RXEMPTY to refresh its value */
> > - litex_write8(membase + OFF_EV_PENDING, EV_TX | EV_RX);
> > + litex_write8(membase + OFF_EV_PENDING, EV_RX);
>
> You're no longer clearing EV_TX, but don't mention why (I understand
> why with the context of the other changes, so perhaps add something to
> this commit message).
I'm adding a separate commit to document this (in v3) as well.
Thanks,
--Gabriel
>
> >
> > /* no overflow bits in status */
> > if (!(uart_handle_sysrq_char(port, ch)))
> > - uart_insert_char(port, status, 0, ch, flg);
> > -
> > - tty_flip_buffer_push(&port->state->port);
> > + uart_insert_char(port, status, 0, ch, TTY_NORMAL);
> > }
> >
> > + tty_flip_buffer_push(&port->state->port);
> > +}
> > +
> > +static void liteuart_timer(struct timer_list *t)
> > +{
> > + struct liteuart_port *uart = from_timer(uart, t, timer);
> > + struct uart_port *port = &uart->port;
> > +
> > + liteuart_rx_chars(port);
> > +
> > mod_timer(&uart->timer, jiffies + uart_poll_timeout(port));
> > }
> >
> > --
> > 2.37.3
> >
