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Date:   Thu, 29 Jul 2021 13:57:44 +0200
From:   Marc Kleine-Budde <mkl@pengutronix.de>
To:     Dan Carpenter <dan.carpenter@oracle.com>
Cc:     Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        wg@grandegger.com, davem@davemloft.net, kuba@kernel.org,
        angelo@kernel-space.org, linux-can@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        kernel-janitors@vger.kernel.org,
        Geert Uytterhoeven <geert@linux-m68k.org>
Subject: Re: [PATCH] can: flexcan: Fix an uninitialized variable issue
Message-ID: <20210729115744.ta5lo42d4metzxtf@pengutronix.de>
References: <a55780a2f4c8f1895b6bcbac4d3f8312b2731079.1627557857.git.christophe.jaillet@wanadoo.fr>
 <20210729113101.n5aucrwu56lyqhg7@pengutronix.de>
 <20210729114442.GT1931@kadam>
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On 29.07.2021 14:44:42, Dan Carpenter wrote:
> On Thu, Jul 29, 2021 at 01:31:01PM +0200, Marc Kleine-Budde wrote:
> > On 29.07.2021 13:27:42, Christophe JAILLET wrote:
> > > If both 'clk_ipg' and 'clk_per' are NULL, we return an un-init value.
> > > So set 'err' to 0, to return success in such a case.
> >=20
> > Thanks for the patch, a similar one has been posted before:
> > https://lore.kernel.org/linux-can/20210728075428.1493568-1-mkl@pengutro=
nix.de/
> >=20
> > > Fixes: d9cead75b1c6 ("can: flexcan: add mcf5441x support")
> > > Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> > > ---
> > > Another way to fix it is to remove the NULL checks for 'clk_ipg' and
> > > 'clk_per' that been added in commit d9cead75b1c6.
> > >=20
> > > They look useless to me because 'clk_prepare_enable()' returns 0 if i=
t is
> > > passed a NULL pointer.
> >=20
> > ACK, while the common clock framework's clk_prepare_enable() can handle
> > NULL pointers, the clock framework used on the mcf5441x doesn't.
>=20
> Huh?  It looks like it just uses the regular stuff?

https://lore.kernel.org/linux-can/CAMuHMdUeeH2BWgVRoVX7yfckY=3Dwi8X3qkaH0TH=
hVF_3FpZsbqg@mail.gmail.com/
Geert Uytterhoeven said:

>> Except that the non-CCF implementation of clk_enable() in
>> arch/m68k/coldfire/clk.c still returns -EINVAL instead of NULL.
>> Any plans to move to CCF? Or at least fix legacy clk_enable().

https://lore.kernel.org/linux-can/7c1151fc-cc28-cbc0-c385-313428b32dd7@kern=
el-space.org/
Angelo Dureghello said:
>> as Geert pointed out, right now without this protection
>> (that shouldn't anyway harm), probe fails:
>>=20
>> [    1.680000] flexcan: probe of flexcan.0 failed with error -22

Maybe it's time to fix the mcf5441x's clk_enable() as Geert pointed out.

regards,
Marc

--=20
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |

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