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gpio: swnode: restore the swnode-name-against-chip-label matching

Using the remote firmware node for software node lookup is the right
thing to do. The GPIO controller we want to resolve should have the
software node we scooped out of the reference attached to it. However,
there are existing users who abuse the software node API by creating
dummy swnodes whose name is set to the expected label string of the GPIO
controller whose pins they want to control and use them in their local
swnode references as GPIO properties.

This used to work when we compared the software node's name to the
chip's label. When we switched to using a real fwnode lookup, these
users broke down because the firmware nodes in question were never
attached to the controllers they were looking for.

Restore the label matching as a fallback to fix the broken users but add
a big FIXME urging for a better solution.

Cc: stable@vger.kernel.org # v6.18, v6.19
Fixes: 216c12047571 ("gpio: swnode: allow referencing GPIO chips by firmware nodes")
Link: https://lore.kernel.org/all/aYkdKfP5fg6iywgr@jekhomev/
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
Link: https://patch.msgid.link/20260211085313.16792-1-bartosz.golaszewski@oss.qualcomm.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>

Bartosz Golaszewski ff91965a 6af6be27

+19
+19
drivers/gpio/gpiolib-swnode.c
··· 42 42 43 43 fwnode_lookup: 44 44 gdev = gpio_device_find_by_fwnode(fwnode); 45 + if (!gdev && gdev_node && gdev_node->name) 46 + /* 47 + * FIXME: We shouldn't need to compare the GPIO controller's 48 + * label against the software node that is supposedly attached 49 + * to it. However there are currently GPIO users that - knowing 50 + * the expected label of the GPIO chip whose pins they want to 51 + * control - set up dummy software nodes named after those GPIO 52 + * controllers, which aren't actually attached to them. In this 53 + * case gpio_device_find_by_fwnode() will fail as no device on 54 + * the GPIO bus is actually associated with the fwnode we're 55 + * looking for. 56 + * 57 + * As a fallback: continue checking the label if we have no 58 + * match. However, the situation described above is an abuse 59 + * of the software node API and should be phased out and the 60 + * following line - eventually removed. 61 + */ 62 + gdev = gpio_device_find_by_label(gdev_node->name); 63 + 45 64 return gdev ?: ERR_PTR(-EPROBE_DEFER); 46 65 } 47 66