On Sunday, May 20, 2018 4:44:31 PM CEST Andy Shevchenko wrote:

On Sun, May 20, 2018 at 12:55 AM, Janusz Krzysztofik

[off-list ref] wrote:

quoted

On Saturday, May 19, 2018 8:00:38 PM CEST Andy Shevchenko wrote:

quoted

On Sat, May 19, 2018 at 2:15 AM, Janusz Krzysztofik [off-list ref]

wrote:

quoted

NULL check in practice discards the _optional part of gpiod_get(). So,
either you use non-optional variant and decide how to handle an
errors, or user _optional w/o NULL check.

OK, I'm going to use something like the below while submitting v2:

-       gpiod_rdy = devm_gpiod_get_optional(&pdev->dev, "rdy", GPIOD_IN);
-       if (!IS_ERR_OR_NULL(gpiod_rdy)) {
-               this->dev_ready = ams_delta_nand_ready;
-       } else {
-               this->dev_ready = NULL;
-               pr_notice("Couldn't request gpio for Delta NAND
ready.\n");
+       priv->gpiod_rdy = devm_gpiod_get_optional(&pdev->dev, "rdy",
+                                                 GPIOD_IN);
+       if (IS_ERR(priv->gpiod_rdy)) {
+               err = PTR_ERR(priv->gpiod_nwp);
+               dev_warn(&pdev->dev, "RDY GPIO request failed (%d)\n",
err); +               goto err_gpiod;

        }

+       if (priv->gpiod_rdy)
+               this->dev_ready = ams_delta_nand_ready;

This makes sense.

Though, I completely dislike "rdy" name of GPIO. Where is it documented?

No documentation files for Amstrad Delta nor for its NAND driver specifically 
exist under Documentation/. However, there exist some for generic GPIO NAND 
driver where the pin name "rdy" is used explicitly:
Documentation/driver-api/gpio/drivers-on-gpio.rst
Documentation/devicetree/bindings/mtd/gpio-control-nand.txt
You can find that mnemonic used across drivers/mtd/nand/, standalone or as a 
suffix, including the Amstrad Delta NAND driver before the change discussed.

To be honest, I don't like it much either, but I'm just using it instead of 
inventing something new.

Thanks,
Janusz