On 29/01/2024 14:55, Linus Walleij wrote: > On Mon, Jan 29, 2024 at 10:40 AM Krzysztof Kozlowski <krzk@xxxxxxxxxx> wrote: >> On 28/01/2024 17:36, Stefan Wahren wrote: > >>> +MODULE_ALIAS("platform:pwm-gpio"); >> >> You should not need MODULE_ALIAS() in normal cases. If you need it, >> usually it means your device ID table is wrong (e.g. misses either >> entries or MODULE_DEVICE_TABLE()). MODULE_ALIAS() is not a substitute >> for incomplete ID table. > > I was under the impression that MODULE_ALIAS > was something people put in to make platforms using > udev behave better by default, e.g. autoprobing these > devices better (on coldplug for "platform:*"). > > For example: > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4f46d6e7e5ffbce0ee1d1a80767fdf45e56cc863 > > But I might have got it all wrong :/ That was 2008 :), but answering to the problem: people put MODULE_ALIAS because they (do not have / forgot / don't want to add)* proper id table for platform devices with MODULE_DEVICE_TABLE. While it works, it does not offer the same scalability as proper ID table and is confusing, because it suggests that driver should be autoloaded by a platform ID, but not matched/bound by platform ID! Such situation is very rare and would deserve a comment anyway. * choose appropriate See also: https://lore.kernel.org/all/?q=f%3Akozlowski+drop+unneeded+module_alias Best regards, Krzysztof