linux-kernel - Re: [PATCH v4 2/2] spi: Add generic SPI multiplexer

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Date:   Tue, 4 Feb 2020 13:07:48 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Chris Packham <Chris.Packham@...iedtelesis.co.nz>
Cc:     "linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH v4 2/2] spi: Add generic SPI multiplexer

On Mon, Feb 3, 2020 at 11:12 PM Chris Packham
<Chris.Packham@...iedtelesis.co.nz> wrote:
> On Mon, 2020-02-03 at 11:50 +0200, Andy Shevchenko wrote:

...

> > > +       priv->mux = devm_mux_control_get(&spi->dev, NULL);
> > > +       ret = PTR_ERR_OR_ZERO(priv->mux);
> >
> > This is a bit complicated.
> >
> > > +       if (ret) {
> >
> > Why not simple do
> >
> >   if (IS_ERR(priv->mux)) {
> >     ret = PTR_ERR(...);
> >     ...
> >   }
> >
> > ?
>
> I've had other maintainers/reviewers suggest the opposite for patches
> I've submitted to other subsystems which is why I went with
> PTR_ERR_OR_ZERO. It also works well with the goto err_put_ctlr; which
> needs ret to be set. It's not exactly a common pattern in the spi code
> so I'd be happy to go the other way if that's the desired convention
> for spi.

Either way is the same amount of lines. The slight difference, that we
don't check for 0. Can you check if generated code is different in
these cases?

-- 
With Best Regards,
Andy Shevchenko