On Tue, Nov 22, 2022 at 08:37:58AM +0100, Jiri Slaby wrote:
> On 21. 11. 22, 14:55, Gabriel L. Somlo wrote:
> > Hi Jiri,
> >
> > Thanks for the feedback!
> >
> > On Mon, Nov 21, 2022 at 09:45:05AM +0100, Jiri Slaby wrote:
> > > On 21. 11. 22, 9:37, Jiri Slaby wrote:
> > > > On 18. 11. 22, 15:55, Gabriel Somlo wrote:
> > > > > Update variable types to match the signature of uart_insert_char()
> > > > > which consumes them.
> > > > >
> > > > > Signed-off-by: Gabriel Somlo <gsomlo@xxxxxxxxx>
> > > > > Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
> > > > > ---
> > > > > drivers/tty/serial/liteuart.c | 3 +--
> > > > > 1 file changed, 1 insertion(+), 2 deletions(-)
> > > > >
> > > > > diff --git a/drivers/tty/serial/liteuart.c
> > > > > b/drivers/tty/serial/liteuart.c
> > > > > index 81aa7c1da73c..42ac9aee050a 100644
> > > > > --- a/drivers/tty/serial/liteuart.c
> > > > > +++ b/drivers/tty/serial/liteuart.c
> > > > > @@ -73,8 +73,7 @@ static void liteuart_timer(struct timer_list *t)
> > > > > struct liteuart_port *uart = from_timer(uart, t, timer);
> > > > > struct uart_port *port = &uart->port;
> > > > > unsigned char __iomem *membase = port->membase;
> > > > > - int ch;
> > > > > - unsigned long status;
> > > > > + unsigned int status, ch;
> > > >
> > > > These should be u8 after all, right?
> >
> > OK, so:
> >
> > - I can hard-code `status` as `1`, like so:
> >
> > while(!litex_read8(membase + OFF_RXEMPTY) {
> > ...
> > if (!(uart_handle_sysrq_char(port, ch)))
> > uart_insert_char(port, 1, 0, ch, TTY_NORMAL);
> >
> > ... since `status` would always be `1` inside the loop. So I'm
> > basically going to get rid of it altogether.
>
> Yes, I had that in my mind. Except passing 1 to uart_insert_char() when
> overflow is hardwired to 0 makes no sense IMO :).
So, looking at what uart_insert_char() does, I could simply do this
instead:
while(!litex_read8(membase + OFF_RXEMPTY) {
...
/* LiteUART does not provide overrun bits */
if (!(uart_handle_sysrq_char(port, ch) ||
tty_insert_flip_char(&port->state->port, ch, TTY_NORMAL)))
++port->icount.buf_overrun;
That is, `tty_insert_flip_char() is the portion of `uart_insert_char()`
that actually gets executed if status is 1 and overrun is 0...
I'm not quite confident about whether this is an improvement in legibility
and/or code quality, but please let me know what *you* think... :)
> > - `ch` is indeed *produced* by `litex_read8()`, which would make it
> > `u8`. It is subsequently *consumed* by `uart_handle_sysrq_char()`
> > and `uart_insert_char()`, which both expect `unsigned int`.
>
> Ignore uart_handle_sysrq_char and uart_insert_char. They should be fixed one
> day. It should really be u8. All down the call chain (it magically turns
> into int in the sysrq handlers, then char is expected).
>
> > If you think it's better to go with the type when the value is
> > produced (as opposed to when it's consumed), I'm OK with that for
> > the upcoming v6 of the series... :)
>
> Yes, please. We should slowly convert _all_ of them.
OK, u8 it is, then.
> > > And can you change membase to u8 * too 8-)?
> >
> > Hmmm, in `struct uart_port` (in include/linux/serial_core.h), the
> > `membase` field is declared as:
> >
> > unsigned char __iomem *membase;
> >
> > which is why I'm thinking we should leave it as-is? Unless there are
> > plans (or a pending patch I'm unaware of) to switch the field in
> > include/linux/serial_core.h to `u8` as well? -- Please advise.
>
> Ah, then keep it. I somehow thought it's void *. And yes, even this should
> be u8 __iomem *, eventually.
OK, it should/will get updated in bulk once that change is made across
the entire subsystem, leaving as-is for now.
Thanks again for all your help and advice!
--Gabriel
