linux-kernel - Re: [PATCH] can: flexcan: Fix an uninitialized variable issue

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Message-ID: <20210729115744.ta5lo42d4metzxtf@pengutronix.de>
Date:   Thu, 29 Jul 2021 13:57:44 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        wg@...ndegger.com, davem@...emloft.net, kuba@...nel.org,
        angelo@...nel-space.org, linux-can@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: Re: [PATCH] can: flexcan: Fix an uninitialized variable issue

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.
> > 
> > Thanks for the patch, a similar one has been posted before:
> > https://lore.kernel.org/linux-can/20210728075428.1493568-1-mkl@pengutronix.de/
> > 
> > > Fixes: d9cead75b1c6 ("can: flexcan: add mcf5441x support")
> > > Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> > > ---
> > > Another way to fix it is to remove the NULL checks for 'clk_ipg' and
> > > 'clk_per' that been added in commit d9cead75b1c6.
> > > 
> > > They look useless to me because 'clk_prepare_enable()' returns 0 if it is
> > > passed a NULL pointer.
> > 
> > ACK, while the common clock framework's clk_prepare_enable() can handle
> > NULL pointers, the clock framework used on the mcf5441x doesn't.
> 
> Huh?  It looks like it just uses the regular stuff?

https://lore.kernel.org/linux-can/CAMuHMdUeeH2BWgVRoVX7yfckY=wi8X3qkaH0THhVF_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@kernel-space.org/
Angelo Dureghello said:
>> as Geert pointed out, right now without this protection
>> (that shouldn't anyway harm), probe fails:
>> 
>> [    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

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
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