Re: [PATCH v3 3/3] gpio: xilinx: Utilize generic bitmap_get_value and _set_value

[Andy Shevchenko]

On Sat, Mar 6, 2021 at 4:08 PM Syed Nayyar Waris <syednwaris@xxxxxxxxx> wrote:
>
> This patch reimplements the xgpio_set_multiple() function in
> drivers/gpio/gpio-xilinx.c to use the new generic functions:
> bitmap_get_value() and bitmap_set_value(). The code is now simpler
> to read and understand. Moreover, instead of looping for each bit
> in xgpio_set_multiple() function, now we can check each channel at
> a time and save cycles.

...

> +       u32 *const state = chip->gpio_state;
> +       unsigned int *const width = chip->gpio_width;

> +

Extra blank line.

> +       DECLARE_BITMAP(old, 64);
> +       DECLARE_BITMAP(new, 64);
> +       DECLARE_BITMAP(changed, 64);

> +       spin_lock_irqsave(&chip->gpio_lock[0], flags);
> +       spin_lock(&chip->gpio_lock[1]);

I understand why this is done at the top of the function in the original code.
I do not understand why you put some operations under spin lock.

Have you checked what each of these spin locks protects?
Please check and try to lock as minimum as possible.

> +       bitmap_set_value(old, 64, state[0], width[0], 0);
> +       bitmap_set_value(old, 64, state[1], width[1], width[0]);
> +       bitmap_replace(new, old, bits, mask, gc->ngpio);
> +
> +       bitmap_set_value(old, 64, state[0], 32, 0);
> +       bitmap_set_value(old, 64, state[1], 32, 32);
> +       state[0] = bitmap_get_value(new, 0, width[0]);
> +       state[1] = bitmap_get_value(new, width[0], width[1]);
> +       bitmap_set_value(new, 64, state[0], 32, 0);
> +       bitmap_set_value(new, 64, state[1], 32, 32);
> +       bitmap_xor(changed, old, new, 64);

Original code and this is cryptic. Can you add a few comments
explaining what is going on here?

> +       spin_unlock(&chip->gpio_lock[1]);
> +       spin_unlock_irqrestore(&chip->gpio_lock[0], flags);

-- 
With Best Regards,
Andy Shevchenko