On Sat, Feb 2, 2013 at 5:29 PM, Alexandre Courbot <acourbot@xxxxxxxxxx> wrote:
> Add a list member to gpio_chip that allows all chips to be parsed
> quickly. The current method requires parsing the entire GPIO integer
> space, which is painfully slow. Using a list makes many chip operations
> that involve lookup or parsing faster, and also simplifies the code. It
> is also necessary to eventually get rid of the global gpio_desc[] array.
>
> The list of gpio_chips is always ordered by base GPIO number to ensure
> chips traversal is done in the right order.
>
> Signed-off-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
OK!
> + * Return -EBUSY if the new chip overlaps with some other chip's integer
> + * space.
(...)
> + /* are we stepping on the chip right before? */
> + if (pos != &gpio_chips && pos->prev != &gpio_chips) {
> + _chip = list_entry(pos->prev, struct gpio_chip, list);
> + if (_chip->base + _chip->ngpio > chip->base) {
> + dev_err(chip->dev,
> + "GPIO integer space overlap, cannot add chip\n");
> + err = -EBUSY;
> + }
> + }
This robustness change on its own is a merit for merging the patch.
And keeping a list of gpiochips available is great for stuff like
debugfs.
Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Yours,
Linus Walleij
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