Re: [PATCH 2/3] gpio: gpio-rz: GPIO driver for Renesas RZ series

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Hi Linus,
    thanks for review

On 11/01/2017 15:55, Linus Walleij wrote:
On Mon, Jan 9, 2017 at 8:31 PM, Jacopo Mondi <jacopo+renesas@xxxxxxxxxx> wrote:


+static void rz_gpio_free(struct gpio_chip *chip, unsigned offset)
+{
+       pinctrl_free_gpio(chip->base + offset);
+
+       /* Set the GPIO as an input to ensure that the next GPIO request won't
+       * drive the GPIO pin as an output.
+       */
+       rz_gpio_direction_input(chip, offset);
+}

Very close to gpiochip_generic_free()

Maybe we should actually set lines as input in the
generic routine!


Is it ok then to simply substitute "pinctrl_free_gpio" with "gpiochip_generic_free" and keep rz_gpio_direction_input here?


+       gpio_chip = &p->gpio_chip;
+       gpio_chip->direction_input = rz_gpio_direction_input;
+       gpio_chip->get = rz_gpio_get;
+       gpio_chip->direction_output = rz_gpio_direction_output;

Please implement .get_direction() as well.


That's funny how a simple addition like this one would require several changes (possibly even in the dts ABI defined by this driver).

This is more a question for the original driver author I hope is listening here:

To read the pin direction I would need to add one more register to the "reg" property range provided in the DTS.
This is of course doable, but I would have two questions here:
- why did you chose to use PMSR register instead of reading/writing directly to PM? Am I missing something? - wouldn't it be better to just receive the port base address from the "reg" property and offset from that instead of having the 3 register addresses specified in the dts?

See, the dts now looks like this:

reg = <0xfcfe3100 0x4>, /* PSR */
      <0xfcfe3200 0x2>, /* PPR */
      <0xfcfe3800 0x4>; /* PMSR */

Shouldn't we just receive the gpiochip base address and the offset as we like?

Thanks
   j
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