On Tue, Sep 26, 2023 at 05:46:07PM -0700, Yury Norov wrote:

On Tue, Sep 26, 2023 at 08:20:07AM +0300, Andy Shevchenko wrote:

quoted

Currently we have a few bitmap calls that are open coded in the library
module. Let's convert them to use generic bitmap APIs instead.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

quoted

+	bitmap_from_arr64(mask, &lv->mask, GPIO_V2_LINES_MAX);
+	bitmap_from_arr64(bits, &lv->bits, GPIO_V2_LINES_MAX);
+
+	num_set = bitmap_gather(vals, bits, mask, lr->num_lines);

It looks like GPIO_V2_LINES_MAX is always 64, and so I wonder: is
my understanding correct that all bits in ->mask and ->bits beyond
lr->num_lines are clear?

The lv fields come from userspace and so cannot be guaranteed to be
zeroed beyond lr->num_lines.  Any set bits beyond that must be ignored,
one way or another.

If so, you can seemingly pass the GPIO_V2_LINES_MAX instead of
lr->num_lines, and that way it will be small_cons_nbits()-optimized.

But that would be decidedly non-optimal for the most common case where
lr->num_lines == 1.

Cheers,
Kent.

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