On 10/21/2015 06:36 PM, Frank Rowand wrote:

On 10/21/2015 1:18 AM, Russell King - ARM Linux wrote:

quoted

On Tue, Oct 20, 2015 at 08:58:19PM -0700, Frank Rowand wrote:

quoted

On 10/20/2015 8:46 AM, Russell King - ARM Linux wrote:

< snip >

quoted

quoted

quoted

+
  static bool driver_deferred_probe_enable = false;
+
  /**
   * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
   *

@@ -188,6 +210,13 @@ static int deferred_probe_initcall(void)
  	driver_deferred_probe_trigger();

Couldn't you put the "driver_deferred_probe_report = true" here?  And then
not add another round of probes.

The idea is not to report anything for drivers that were deferred
during the normal bootup.  The above is part of the normal bootup,
and the deferred activity should not be warned about.

The above is currently the last point for probe to succeed or defer
(until possibly, as you mentioned, module loading resolves the defer).
If a probe defers above, it will defer again below.  The set of defers
should be exactly the same above and below.

Unfortunately this is not "the last point for probe to succeed or defer".
There are still a bunch of drivers in Kernel which will be probed at late_initcall() level.
(like ./drivers/net/ethernet/ti/cpsw.c => late_initcall(cpsw_init);
Yes - they probably need to be updated to use module_init(), but that's what
we have now). Those drivers will re-trigger deferred device probing if their
probe succeeded.

As result, it is impossible to say when will it happen the 
"final round of deferred device probing" :( and final list of drivers which
was "deferred forever" will be know only when kernel exits to User space 
("deferred forever" - before loading modules).

May be, we also can consider adding debug_fs entry which can be used to display
actual state of deferred_probe_pending_list? 

quoted

If we have any devices still deferring after _this_ round, that must
indicate that some resource they want is not available, and that
should be warned about.

Of course, modules can defer too - and I made some suggestions in my
waffle above the patch about that.

< adding back trimmed, for fuller context >

quoted

quoted

quoted

  	/* Sort as many dependencies as possible before exiting initcalls */
  	flush_workqueue(deferred_wq);
+
+	/* Now one final round, reporting any devices that remain deferred */
+	driver_deferred_probe_report = true;
+	driver_deferred_probe_trigger();
+	/* Sort as many dependencies as possible before exiting initcalls */
+	flush_workqueue(deferred_wq);
+
  	return 0;
  }

-- 
regards,
-grygorii