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[RFC,2/3] iio: bu27008: Probe asynchronously

Message ID 7cbc13bb62a0f6919366317991c5f451a0f8aa4e.1683185765.git.mazziesaccount@gmail.com
State New
Headers
Series ROHM Sensor async probing |

Commit Message

Matti Vaittinen May 4, 2023, 7:58 a.m. UTC 
  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.

The BU27008 gets probe delayed for at least two reasons. It enables the
supply regulator, (which is likely to have ramp-up delay if it was
disabled) and additionally it delays while the sensor itself is
initializing.

Changing to asynchronous probing may cause problems. Some of which are
discussed in:
https://lore.kernel.org/all/06db017f-e985-4434-8d1d-02ca2100cca0@sirena.org.uk/

Enabling async probing for the ROHM BU27008 should be fairly safe to try
though as there is no in-tree users for it yet. If the async probing
appears to be an issue we can switch easily back to synchronous (or
better yet, fix the actual problem).

Enable asynchronous probing for BU27008.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>

---

I am unsure if this change is 100% safe - but I don't immediately see
the harm. Please let me know if some of you have more experience on
problems when using asynchronous probing with IIO devices.
---
 drivers/iio/light/rohm-bu27008.c | 1 +
 1 file changed, 1 insertion(+)
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Patch

diff --git a/drivers/iio/light/rohm-bu27008.c b/drivers/iio/light/rohm-bu27008.c
index c04d845062ba..628d17036bb4 100644
--- a/drivers/iio/light/rohm-bu27008.c
+++ b/drivers/iio/light/rohm-bu27008.c
@@ -982,6 +982,7 @@  static struct i2c_driver bu27008_i2c_driver = {
 	.driver = {
 		.name = "bu27008",
 		.of_match_table = bu27008_of_match,
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
 	},
 	.probe_new = bu27008_probe,
 };