This is a note to let you know that I've just added the patch titled driver core: Don't require dynamic_debug for initcall_debug probe timing to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: driver-core-don-t-require-dynamic_debug-for-initcall_debug-probe-timing.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From e2f06aa885081e1391916367f53bad984714b4db Mon Sep 17 00:00:00 2001 From: Stephen Boyd <swboyd@xxxxxxxxxxxx> Date: Wed, 12 Apr 2023 15:58:42 -0700 Subject: driver core: Don't require dynamic_debug for initcall_debug probe timing From: Stephen Boyd <swboyd@xxxxxxxxxxxx> commit e2f06aa885081e1391916367f53bad984714b4db upstream. Don't require the use of dynamic debug (or modification of the kernel to add a #define DEBUG to the top of this file) to get the printk message about driver probe timing. This printk is only emitted when initcall_debug is enabled on the kernel commandline, and it isn't immediately obvious that you have to do something else to debug boot timing issues related to driver probe. Add a comment too so it doesn't get converted back to pr_debug(). Fixes: eb7fbc9fb118 ("driver core: Add missing '\n' in log messages") Cc: stable <stable@xxxxxxxxxx> Cc: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx> Cc: Brian Norris <briannorris@xxxxxxxxxxxx> Reviewed-by: Brian Norris <briannorris@xxxxxxxxxxxx> Acked-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx> Link: https://lore.kernel.org/r/20230412225842.3196599-1-swboyd@xxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/base/dd.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -677,7 +677,12 @@ static int really_probe_debug(struct dev calltime = ktime_get(); ret = really_probe(dev, drv); rettime = ktime_get(); - pr_debug("probe of %s returned %d after %lld usecs\n", + /* + * Don't change this to pr_debug() because that requires + * CONFIG_DYNAMIC_DEBUG and we want a simple 'initcall_debug' on the + * kernel commandline to print this all the time at the debug level. + */ + printk(KERN_DEBUG "probe of %s returned %d after %lld usecs\n", dev_name(dev), ret, ktime_us_delta(rettime, calltime)); return ret; } Patches currently in stable-queue which might be from swboyd@xxxxxxxxxxxx are queue-5.10/driver-core-don-t-require-dynamic_debug-for-initcall_debug-probe-timing.patch