Re: [PATCH] gpio: Ignore gpio names with empty strings

[Brandon Maier <brandon.maier@xxxxxxxxxxxxxxxxxxx>]

On Wed, Oct 10, 2018 at 4:12 AM, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:

> Isn't the real problem that they should be passing NULL
> rather than "" empty string for line names?

In our case, we are using the gpio_chip->names in place of
gpio-line-names. Because Xilinx's drivers/gpio/gpio-xilinx allocates
multiple gpio_chips under a single devicetree node, gpio-line-names
won't work. This is the same problem mentioned in Hedges Alexander's
port of gpio-xilinx[1]. I worked around this by adding a
gpio-line-names-2 that the second chip grabs and passes in through
gpio_chip->names.

This patch seemed appropriate because the intent of an "empty string"
in gpio-line-names is to be an unset gpio name. It would also prevent
name collisions from happening if we added name collision detection to
gpio-line-names. But if it's better to leave this as-is, I could
modify our code to replace "" -> NULL in gpio-xilinx.

[1] https://www.spinics.net/lists/linux-gpio/msg31773.html

Thanks,
Brandon Maier