[PATCH] gpio: mxs: implement get_direction callback

[u.kleine-koenig@pengutronix.de (Uwe Kleine-König)]

Hello Richard,

On Mon, Nov 17, 2014 at 09:31:21AM +0100, Richard Genoud wrote:
> 2014-11-16 22:42 GMT+01:00 Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>:
> > On Sat, Nov 15, 2014 at 08:29:04PM +0100, Janusz U?ycki wrote:
> >> The commit f9e42397d79b6e810437ba1130b0b4b594f5e56c
> >> ("serial: mxs-auart: add interrupts for modem control lines")
> >> is based on Richard's commit ab5e4e4108ca5d8326cb6b4b3a21b096a002f68f
> >> ("tty/serial: at91: add interrupts for modem control lines").
> >> Both patches use the condition:
> >> "if (gpiod && (gpiod_get_direction(gpiod) == GPIOF_DIR_IN))"
> > This is broken. Actually you want to loop only over the functions in
> > mctrl_gpios_desc that are inputs (i.e. CTS, DSR, DCD and RNG) and don't
> > depend on the hardware state and/or a working gpiod_get_direction.
> Yes, it seemed a convenient test to locate inputs in atmel_serial's
> probe function.
> But you're right, looping on a
> enum mctrl_gpio_idx [] = {
>         UART_GPIO_CTS, UART_GPIO_DSR,
>         UART_GPIO_DCD, UART_GPIO_RNG, UART_GPIO_RI
> };
> Would better describe what is done, without using gpiod_get_direction().
Note that UART_GPIO_RNG == UART_GPIO_RI. And this is also something that
could be handled be generic code, so the respective mctrl_gpio function
can just loop over mctrl_gpios_desc and skip the entries with
dir_out=true.

Best regards
Uwe

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