+
+ chip = gpiod_to_chip(desc);
+ /*
+ * If pin hardware number of array member 0 is also 0, select
+ * its chip as a candidate for fast bitmap processing path.
+ */
+ if (descs->ndescs == 0 && gpio_chip_hwgpio(desc) == 0) {
+ struct gpio_descs *array;
+
+ bitmap_size = BITS_TO_LONGS(chip->ngpio > count ?
+ chip->ngpio : count);
+
+ array = kzalloc(struct_size(descs, desc, count) +
+ struct_size(array_info, invert_mask,
+ 3 * bitmap_size), GFP_KERNEL);
+ if (!array) {
+ gpiod_put_array(descs);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ memcpy(array, descs,
+ struct_size(descs, desc, descs->ndescs + 1));
+ kfree(descs);
+
+ descs = array;
+ array_info = (void *)(descs->desc + count);
+ array_info->get_mask = array_info->invert_mask +
+ bitmap_size;
+ array_info->set_mask = array_info->get_mask +
+ bitmap_size;
+
+ array_info->desc = descs->desc;
+ array_info->size = count;
+ array_info->chip = chip;
+ bitmap_set(array_info->get_mask, descs->ndescs,
+ count - descs->ndescs);
+ bitmap_set(array_info->set_mask, descs->ndescs,
+ count - descs->ndescs);
+ descs->info = array_info;
+ }
+ /* Unmark array members which don't belong to the 'fast' chip */
+ if (array_info && array_info->chip != chip) {
+ __clear_bit(descs->ndescs, array_info->get_mask);
+ __clear_bit(descs->ndescs, array_info->set_mask);
+ }
+ /*
+ * Detect array members which belong to the 'fast' chip
+ * but their pins are not in hardware order.
+ */
+ else if (array_info &&
+ gpio_chip_hwgpio(desc) != descs->ndescs) {
+ /*
+ * Don't use fast path if all array members processed so
+ * far belong to the same chip as this one but its pin
+ * hardware number is different from its array index.
+ */
+ if (bitmap_full(array_info->get_mask, descs->ndescs)) {
+ array_info = NULL;
+ } else {
+ __clear_bit(descs->ndescs,
+ array_info->get_mask);
+ __clear_bit(descs->ndescs,
+ array_info->set_mask);
+ }
+ } else if (array_info) {
+ /* Exclude open drain or open source from fast output */
+ if (gpiochip_line_is_open_drain(chip, descs->ndescs) ||
+ gpiochip_line_is_open_source(chip, descs->ndescs))
+ __clear_bit(descs->ndescs,
+ array_info->set_mask);
+ /* Identify 'fast' pins which require invertion */
+ if (gpiod_is_active_low(desc))
+ __set_bit(descs->ndescs,
+ array_info->invert_mask);
+ }
+