linux-kernel - Re: [PATCH 02/10] phy: Add configuration interface

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Message-ID: <20180906162450.GA26997@lunn.ch>
Date:   Thu, 6 Sep 2018 18:24:50 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Maxime Ripard <maxime.ripard@...tlin.com>
Cc:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Archit Taneja <architt@...eaurora.org>,
        Krzysztof Witos <kwitos@...ence.com>,
        Rafal Ciepiela <rafalc@...ence.com>,
        Boris Brezillon <boris.brezillon@...tlin.com>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        Kishon Vijay Abraham I <kishon@...com>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org
Subject: Re: [PATCH 02/10] phy: Add configuration interface

> > > +int phy_configure(struct phy *phy, enum phy_mode mode,
> > > +		  union phy_configure_opts *opts)
> > > +{
> > > +	int ret;
> > > +
> > > +	if (!phy)
> > > +		return -EINVAL;
> > > +
> > > +	if (!phy->ops->configure)
> > > +		return 0;
> > 
> > Shouldn't you report an error to the caller ? If a caller expects the PHY to 
> > be configurable, I would assume that silently ignoring the requested 
> > configuration won't work great.
> 
> I'm not sure. I also expect a device having to interact with multiple
> PHYs, some of them needing some configuration while some other do
> not. In that scenario, returning 0 seems to be the right thing to do.

You could return -EOPNOTSUPP. That is common in the network stack. The
caller then has the information to decide if it should keep going, or
return an error.

       Andrew