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SubjectRe: [PATCH 2/2 v5] tty/serial/8250: use mctrl_gpio helpers
On Tue, Jun 11, 2019 at 12:56:03PM +0200, Stefan Roese wrote:
> From: Yegor Yefremov <yegorslists@googlemail.com>
>
> This patch permits the usage for GPIOs to control
> the CTS/RTS/DTR/DSR/DCD/RI signals.

> static inline void serial8250_out_MCR(struct uart_8250_port *up, int value)
> {
> serial_out(up, UART_MCR, value);
> +
> + if (up->gpios) {
> + int mctrl_gpio = 0;
> +
> + if (value & UART_MCR_RTS)
> + mctrl_gpio |= TIOCM_RTS;
> + if (value & UART_MCR_DTR)
> + mctrl_gpio |= TIOCM_DTR;
> +
> + mctrl_gpio_set(up->gpios, mctrl_gpio);
> + }
> }
>
> static inline int serial8250_in_MCR(struct uart_8250_port *up)
> {
> - return serial_in(up, UART_MCR);
> + int mctrl;
> +
> + mctrl = serial_in(up, UART_MCR);
> +
> + if (up->gpios) {
> + int mctrl_gpio = 0;
> +
> + /* save current MCR values */
> + if (mctrl & UART_MCR_RTS)
> + mctrl_gpio |= TIOCM_RTS;
> + if (mctrl & UART_MCR_DTR)
> + mctrl_gpio |= TIOCM_DTR;
> +
> + mctrl_gpio = mctrl_gpio_get_outputs(up->gpios, &mctrl_gpio);
> + if (mctrl_gpio & TIOCM_RTS)
> + mctrl |= UART_MCR_RTS;
> + else
> + mctrl &= ~UART_MCR_RTS;
> +
> + if (mctrl_gpio & TIOCM_DTR)
> + mctrl |= UART_MCR_DTR;
> + else
> + mctrl &= ~UART_MCR_DTR;
> + }
> +
> + return mctrl;
> }

These are using OR logic with potentially volatile data. Shouldn't we mask
unused bits in UART_MCR in case of up->gpios != NULL?

> + if (up->gpios == 0)

This is type inconsistency with this check as far as I understand.
I guess you have to do either (up->gpios == NULL), or (!up->gpios).

> ret = 0;

+ Blank line.

> + if (up->gpios)
> + return mctrl_gpio_get(up->gpios, &ret);

--
With Best Regards,
Andy Shevchenko


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