Devices which may take a while to initialize during probe and which have no strong reason to probe synchronously can request asynchronous probing as default probe strategy. This can speed-up start times on some platforms. There is however some caveats listed for asynchronous probing for example here: https://lore.kernel.org/all/06db017f-e985-4434-8d1d-02ca2100cca0@xxxxxxxxxxxxx/ I don't know how tolerant IIO users are what comes to asynchronous probing but I _guess_ this is (and should be) handled pretty well. Still, guessing could be said to be somewhat sub-optimal when doing kernel development :) Hence this RFC - if someone has better understanding on async probing when using IIO, please let me know! As far as I know these drivers do not currently have in-tree users. Furthemore, they are so new they don't probably have many user-space users either. In fact, the BU27034 is not yet in any official releases and BU27008 is not merged in any official trees yet. Thus, testing out async probing with them should not break existing users. KX022A is also relatively new and I don't think it has yet been widely used either. Finally, if asynchronous probing does break things, then: a) We should try fix the thing preventing async probe. b) We can pretty easily revert back to synchronous probing. Please note that the patch 2 depends on https://lore.kernel.org/lkml/cover.1683105758.git.mazziesaccount@xxxxxxxxx/ which is not yet in-tree. If the feed-back from this RFC is positive, then I will squash this change to that series when re-spinning it next time. Please note that the patch 3 depends on bu27034 series which is expected to land on 6.4-rc1. --- Matti Vaittinen (3): iio: bu27034: Probe asynchronously iio: bu27008: Probe asynchronously iio: kx022a: Probe asynchronously drivers/iio/accel/kionix-kx022a-i2c.c | 1 + drivers/iio/accel/kionix-kx022a-spi.c | 1 + drivers/iio/light/rohm-bu27008.c | 1 + drivers/iio/light/rohm-bu27034.c | 1 + 4 files changed, 4 insertions(+) -- 2.40.0 -- Matti Vaittinen, Linux device drivers ROHM Semiconductors, Finland SWDC Kiviharjunlenkki 1E 90220 OULU FINLAND ~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~ Simon says - in Latin please. ~~~ "non cogito me" dixit Rene Descarte, deinde evanescavit ~~~ Thanks to Simon Glass for the translation =]
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