Hi Richard,

On Wed, Aug 21, 2019 at 5:27 PM Richard Genoud <richard.gen...@gmail.com> wrote:
> Le 20/08/2019 à 17:47, Richard Genoud a écrit :
> > Le 14/08/2019 à 13:08, Uwe Kleine-König a écrit :
> >> On Wed, Aug 14, 2019 at 12:20:33PM +0200, Geert Uytterhoeven wrote:
> >>> Hi Uwe,
> >>>
> >>> On Wed, Aug 14, 2019 at 11:36 AM Uwe Kleine-König
> >>> <u.kleine-koe...@pengutronix.de> wrote:
> >>>> On Wed, Aug 14, 2019 at 11:29:22AM +0200, Geert Uytterhoeven wrote:
> >>>>> Since commit 1d267ea6539f2663 ("serial: mctrl-gpio: simplify init
> >>>>> routine"), mctrl_gpio_init() returns failure if the assignment to any
> >>>>> member of the gpio array results in an error pointer.
> >>>>> Since commit c359522194593815 ("serial: mctrl_gpio: Avoid probe failures
> >>>>> in case of missing gpiolib"), mctrl_gpio_to_gpiod() returns NULL in the
> >>>>> !CONFIG_GPIOLIB case.
> >>>>> Hence there is no longer a need to check for mctrl_gpio_to_gpiod()
> >>>>> returning an error value.  A simple NULL check is sufficient.
> >>>>>
> >>>>> This follows the spirit of commit 445df7ff3fd1a0a9 ("serial: mctrl-gpio:
> >>>>> drop usages of IS_ERR_OR_NULL") in the mctrl-gpio core.
> >>>>>
> >>>>> Signed-off-by: Geert Uytterhoeven <geert+rene...@glider.be>
> >>>>> ---
> >>>>>  drivers/tty/serial/atmel_serial.c | 12 ++++--------
> >>>>>  1 file changed, 4 insertions(+), 8 deletions(-)
> >>>>>
> >>>>> diff --git a/drivers/tty/serial/atmel_serial.c 
> >>>>> b/drivers/tty/serial/atmel_serial.c
> >>>>> index 19a85d6fe3d20541..e9620a81166b7dc1 100644
> >>>>> --- a/drivers/tty/serial/atmel_serial.c
> >>>>> +++ b/drivers/tty/serial/atmel_serial.c
> >>>>> @@ -303,32 +303,28 @@ static unsigned int atmel_get_lines_status(struct 
> >>>>> uart_port *port)
> >>>>>
> >>>>>       mctrl_gpio_get(atmel_port->gpios, &ret);
> >>>>>
> >>>>> -     if (!IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(atmel_port->gpios,
> >>>>> -                                             UART_GPIO_CTS))) {
> >>>>> +     if (mctrl_gpio_to_gpiod(atmel_port->gpios, UART_GPIO_CTS)) {
> >>>>>               if (ret & TIOCM_CTS)
> >>>>>                       status &= ~ATMEL_US_CTS;
> >>>>>               else
> >>>>>                       status |= ATMEL_US_CTS;
> >>>>>       }
> >>>>
> >>>> The change is fine, but it seems the atmel driver doesn't use mctrl_gpio
> >>>> as expected (at least as expected by me). IMHO driving the hardware
> >>>> function of the CTS pin shouldn't be conditional on the presence of a
> >>>> cts-gpio. Is there a reason not to just drop the if completely?
> >>>
> >>> The above code returns the hardware status if CTS is not a GPIO, and
> >>> returns (overrides with) the GPIO status if CTS is a GPIO.
> >>> Isn't that correct, or am I missing something?
> >>
> >> I took a deeper look into this driver now. The task for
> >> atmel_get_lines_status() isn't to implement the get_mctrl() callback.
> >>
> >> Instead this is called in the irqhandler to set ATMEL_US_RI in a
> >> "pending" value that then later in atmel_handle_status() is translated
> >> to a "ring" event that is handled there.
> >>
> >> So the right cleanup would be to let atmel_get_lines_status() just be
> >>
> >>      return atmel_uart_readl(port, ATMEL_US_CSR);
> >>
> >> . If something happend on the lines implemented as gpio the driver's irq
> >> function isn't called anyhow.
> >
> > I'd like to give it a good test to be sure, and I'll get back to you.
>
> So, Uwe is right.
> Since commit ce59e48fdbad ("serial: mctrl_gpio: implement interrupt 
> handling"),
> atmel_get_lines_status() can be completly killed and replaced by :
> atmel_uart_readl(port, ATMEL_US_CSR);
>
> Geert, do you want to send a patch for that, or should I do it ?

Feel free to send a  patch.
I don't have the Atmel hardware  anyway.
Thanks!

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

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