diff mbox series

[v1,2/3] serial: liteuart: separate RX loop from poll timer

Message ID 20221107171500.2537938-3-gsomlo@gmail.com
State New
Headers
Series serial: liteuart: add IRQ support |

Commit Message

Gabriel L. Somlo Nov. 7, 2022, 5:14 p.m. UTC 
  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@gmail.com>
---
 drivers/tty/serial/liteuart.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

Comments

Joel Stanley Nov. 10, 2022, 1:09 a.m. UTC | #1 
On Mon, 7 Nov 2022 at 17:15, Gabriel Somlo <gsomlo@gmail.com> 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@gmail.com>
> ---
>  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.

>
>         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).


>
>                 /* 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
>
Gabriel L. Somlo Nov. 11, 2022, 5:06 p.m. UTC | #2 
On Thu, Nov 10, 2022 at 01:09:59AM +0000, Joel Stanley wrote:
> On Mon, 7 Nov 2022 at 17:15, Gabriel Somlo <gsomlo@gmail.com> 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@gmail.com>
> > ---
> >  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
> >
diff mbox series

Patch

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;
 
 	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);
 
 		/* 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));
 }