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From:   Andy Duan <fugang.duan@nxp.com>
To:     David Miller <davem@davemloft.net>,
        "hslester96@gmail.com" <hslester96@gmail.com>
CC:     "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [EXT] Re: [PATCH net v2] net: fec: add a check for CONFIG_PM to
 avoid clock count mis-match
Thread-Topic: [EXT] Re: [PATCH net v2] net: fec: add a check for CONFIG_PM to
 avoid clock count mis-match
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Date:   Wed, 13 Nov 2019 01:50:20 +0000
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 <20191112.111318.1764384720609728917.davem@davemloft.net>
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From: David Miller <davem@davemloft.net> Sent: Wednesday, November 13, 2019=
 3:13 AM
> From: Chuhong Yuan <hslester96@gmail.com>
> Date: Tue, 12 Nov 2019 19:28:30 +0800
>=20
> > If CONFIG_PM is enabled, runtime pm will work and call runtime_suspend
> > automatically to disable clks.
> > Therefore, remove only needs to disable clks when CONFIG_PM is disabled=
.
> > Add this check to avoid clock count mis-match caused by double-disable.
> >
> > Fixes: c43eab3eddb4 ("net: fec: add missed clk_disable_unprepare in
> > remove")
> > Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
>=20
> I don't understand this at all.
>=20
> The clk disables here match the unconditional clk enables in the probe
> function.
>=20
> And that is how this is supposed to work, probe enables match remove
> disables.  And suspend disables match resume enables.
>=20
> Why isn't the probe enable taking the correct count, which the remove
> function must match with an appropriate disable?  There is no CONFIG_PM
> guarding the probe time clk enables.

Current driver runtime pm callback enable/disable clk_ipg/clk_ahb two clks.
CONFIG_PM is a optional config, if CONFIG_PM is disabled, runtime callbacks=
 will
Not be called.
The driver enable clk_ipg/clk_ahb two clks during probe, and depends runtim=
e
suspend to disable the two clks if CONFIG_PM is enabled.

In driver remove() also need to disable the two clks if CONIFG_PM is disabl=
ed.
So the patch c43eab3eddb4 ("net: fec: add missed clk_disable_unprepare in e=
move")
target the fixes if CONFIG_PM is not enabled, but the patch ignore to check=
 the=20
CONFIG_PM that make clock count mismatch in CONFIG_PM enabled case.

Andy