Hi Saravana,
Thanks for your patch!
On Thu, Jun 25, 2020 at 5:24 AM Saravana Kannan <sarava...@google.com> wrote:
> Under the following conditions:
> - driver A is built in and can probe device-A
> - driver B is a module and can probe device-B
I think this is not correct: in my case driver B is builtin, too.
> - device-A is supplier of device-B
>
> Without this patch:
> 1. device-A is added.
> 2. device-B is added.
> 3. dpm_list is now [device-A, device-B].
> 4. driver-A defers probe of device-A.
> 5. deferred probe of device-A is reattempted
I think this is misleading: in my case driver-A did not defer the probe
of device-A, and driver-A never returned -EPROBE_DEFER.
Probing was merely paused, due to fw_devlink_pause();
> 6. device-A is moved to end of dpm_list.
> 6. dpm_list is now [device-B, device-A].
> 7. driver-B is loaded and probes device-B.
> 8. dpm_list stays as [device-B, device-A].
>
> Suspend (which goes in the reverse order of dpm_list) fails because
> device-A (supplier) is suspended before device-B (consumer).
>
> With this patch:
> 1. device-A is added.
> 2. device-B is added.
> 3. dpm_list is now [device-A, device-B].
> 4. driver-A defers probe of device-A.
> 5. deferred probe of device-A is reattempted later.
> 6. dpm_list is now [device-B, device-A].
> 7. driver-B is loaded and probes device-B.
> 8. dpm_list is now [device-A, device-B].
>
> Suspend works because device-B (consumer) is suspended before device-A
> (supplier).
>
> Fixes: 494fd7b7ad10 ("PM / core: fix deferred probe breaking suspend resume
> order")
> Fixes: 716a7a259690 ("driver core: fw_devlink: Add support for batching
> fwnode parsing")
> Cc: Geert Uytterhoeven <ge...@linux-m68k.org>
> Signed-off-by: Saravana Kannan <sarava...@google.com>
This fixes wake-up by GPIO key on r8a7740/armadillo and sh73a0/kzm9g.
Tested-by: Geert Uytterhoeven <geert+rene...@glider.be>
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -109,6 +109,8 @@ static void deferred_probe_work_func(struct work_struct
> *work)
> * probe makes that very unsafe.
> */
> device_pm_move_to_tail(dev);
> + /* Greg/Rafael: SHOULD I DELETE THIS? ^^ I think I should, but
> + * I'm worried if it'll have some unintended consequeneces. */
Works fine for me with the call to device_pm_move_to_tail() removed, too
(at least on the two boards that showed the issue before).
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
