netdev - Re: [PATCH v5] sh_eth: ensure pm_runtime cannot suspend the device during init

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Date:	Fri, 21 Mar 2014 13:14:59 +0100
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Ben Dooks <ben.dooks@...ethink.co.uk>
Cc:	linux-kernel@...ts.codethink.co.uk,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Linux-sh list <linux-sh@...r.kernel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
	Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
Subject: Re: [PATCH v5] sh_eth: ensure pm_runtime cannot suspend the device
 during init

Hi Ben,

On Fri, Mar 21, 2014 at 12:09 PM, Ben Dooks <ben.dooks@...ethink.co.uk> wrote:
> The pm_rumtime work queue is causing the device to be suspended during
> initialisation, thus the initialisation may not be able to access registers
> properly. As the code is called from a work queue, it is possible that this
> is not seen from certain configurations/builds due to the asynchronos
> nature of the code.
>
> Another issue has also been found where the network device registration
> calls back into the driver thus causing further pm_runtime calls that
> also caused issues with the MDIO bus code. This has now been checked
> and is the only place the MDIO can be called without the device open.
>
> Use pm_runtime_get_sync() and pm_runtime_put() to ensure that the
> pm system does not suspend it during the probe() call and remove the
> now unnecessary pm_runtime_resume() call. Also add a call in the error
> path to call pm_runtime_disable().
>
> This fixes the external abort that can cause /sbin/init or other such
> init processed to die.
>
> Signed-off-by: Ben Dooks <ben.dooks@...ethink.co.uk>
> Tested-by: Geert Uytterhoeven <geert@...ux-m68k.org>

Thanks, still works!

> ---
> Cc: sergei.shtylyov@...entembedded.com
> Cc: laurent.pinchart+renesas@...asonboard.com
> cc: netdev@...r.kernel.org
>
> Note, Laurent this should probably be applied before your
> current series as it may require changes to the exit sequence.

I guess this should read:

" Fixed from v4:
          - rebased on top of netdev-next"

?

> Fixes from v1:
>         - use pm_runtime_put() over pm_runtime_put_sync() as
>           we do not need to guaranteed the device has powered
>           off after probe.
>
> Fixed from v2:
>         - call pm_runtime_put() in error path
>
> Fixed from v3:
>         - call pm_runtime_disable() in error path

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-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
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