Re: [PATCH v3 06/11] serial: sc16is7xx: fix bug when first setting GPIO direction

From: andy . shevchenko
Date: Thu May 25 2023 - 07:10:46 EST

Thu, May 25, 2023 at 12:03:20AM -0400, Hugo Villeneuve kirjoitti:
> From: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
> When we want to configure a pin as an output pin with a value of logic
> 0, we end up as having a value of logic 1 on the output pin. Setting a
> logic 0 a second time (or more) after that will correctly output a
> logic 0 on the output pin.
> By default, all GPIO pins are configured as inputs. When we enter
> c16is7xx_gpio_direction_output() for the first time, we first set the

Missing 's'.

> desired value in IOSTATE, and then we configure the pin as an output.
> The datasheet states that writing to IOSTATE register will trigger a
> transfer of the value to the I/O pin configured as output, so if the
> pin is configured as an input, nothing will be transferred.
> Therefore, set the direction first in IODIR, and then set the desired
> value in IOSTATE.
> This is what is done in NXP application note AN10587.

With Best Regards,
Andy Shevchenko