[PATCH] driver core: Make probe deferral more quiet

[PATCH] driver core: Make probe deferral more quiet

[Mark Brown]

Currently probe deferral prints a message every time a device requests
deferral at info severity (which is displayed by default). This can have
an impact on system boot times with serial consoles and is generally quite
noisy.

Since subsystems and drivers should already be logging the specific reason
for probe deferral in order to aid users in understanding problems the
messages from the driver core should be redundant lower the severity of
the messages printed, cutting down on the volume of output on the console.

This does mean that if the drivers and subsystems aren't doing a good job
we get no output on the console by default. Ideally we'd be able to arrange
to print if nothing else printed, though that's a little fun. Even better
would be to come up with a mechanism that explicitly does dependencies so
we don't have to keep polling and erroring.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
 drivers/base/dd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index cdc779cf79a3..a3abe628aa8d 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -322,7 +322,7 @@ probe_failed:
 
 	if (ret == -EPROBE_DEFER) {
 		/* Driver requested deferred probing */
-		dev_info(dev, "Driver %s requests probe deferral\n", drv->name);
+		dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
 		driver_deferred_probe_add(dev);
 		/* Did a trigger occur while probing? Need to re-trigger if yes */
 		if (local_trigger_count != atomic_read(&deferred_trigger_count))
-- 
2.1.4

Re: [PATCH] driver core: Make probe deferral more quiet

[Bjorn Andersson]

On Tue 10 Mar 04:55 PDT 2015, Mark Brown wrote:

> Currently probe deferral prints a message every time a device requests
> deferral at info severity (which is displayed by default). This can have
> an impact on system boot times with serial consoles and is generally quite
> noisy.
> 
> Since subsystems and drivers should already be logging the specific reason
> for probe deferral in order to aid users in understanding problems the
> messages from the driver core should be redundant lower the severity of
> the messages printed, cutting down on the volume of output on the console.
> 
> This does mean that if the drivers and subsystems aren't doing a good job
> we get no output on the console by default. Ideally we'd be able to arrange
> to print if nothing else printed, though that's a little fun. Even better
> would be to come up with a mechanism that explicitly does dependencies so
> we don't have to keep polling and erroring.
> 
> Signed-off-by: Mark Brown <broonie@kernel.org>

I like it, much better than the suggestion I made to drop the more
informative print out in the regulator framework.

Reviewed-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>

Regards,
Bjorn