netdev - Re: [PATCH 1/2] ALSA: ppc: drop if block with always false condition

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Message-ID: <20201127094547.4zcyeycfrriitkqx@pengutronix.de>
Date:   Fri, 27 Nov 2020 10:45:47 +0100
From:   Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Geoff Levand <geoff@...radead.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Jens Axboe <axboe@...nel.dk>, Jim Paris <jim@...n.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Alan Stern <stern@...land.harvard.edu>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        ALSA Development Mailing List <alsa-devel@...a-project.org>,
        linux-block@...r.kernel.org, netdev <netdev@...r.kernel.org>,
        scsi <linux-scsi@...r.kernel.org>,
        USB list <linux-usb@...r.kernel.org>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Linux Fbdev development list <linux-fbdev@...r.kernel.org>
Subject: Re: [PATCH 1/2] ALSA: ppc: drop if block with always false condition

On Fri, Nov 27, 2020 at 09:35:39AM +0100, Geert Uytterhoeven wrote:
> Hi Uwe,
> 
> On Thu, Nov 26, 2020 at 6:03 PM Uwe Kleine-König
> <u.kleine-koenig@...gutronix.de> wrote:
> > The remove callback is only called for devices that were probed
> > successfully before. As the matching probe function cannot complete
> > without error if dev->match_id != PS3_MATCH_ID_SOUND, we don't have to
> > check this here.
> >
> > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
> 
> Thanks for your patch!
> 
> Reviewed-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> 
> Note that there are similar checks in snd_ps3_driver_probe(), which
> can be removed, too:
> 
>         if (WARN_ON(!firmware_has_feature(FW_FEATURE_PS3_LV1)))
>                 return -ENODEV;
>         if (WARN_ON(dev->match_id != PS3_MATCH_ID_SOUND))
>                 return -ENODEV;

I had to invest some brain cycles here. For the first:

Assuming firmware_has_feature(FW_FEATURE_PS3_LV1) always returns the
same value, snd_ps3_driver_probe is only used after this check succeeds
because the driver is registered only after this check in
snd_ps3_init().

The second is superflous because ps3_system_bus_match() yields false if
this doesn't match the driver's match_id.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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