netdev - Re: [PATCH v3 7/8] net: phy: Add support to configure clock in Broadcom iProc mdio mux

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Date:   Wed, 1 Aug 2018 22:38:46 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Russell King - ARM Linux <linux@...linux.org.uk>
Cc:     Arun Parameswaran <arun.parameswaran@...adcom.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Ray Jui <rjui@...adcom.com>,
        Scott Branden <sbranden@...adcom.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>, netdev@...r.kernel.org,
        bcm-kernel-feedback-list@...adcom.com,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v3 7/8] net: phy: Add support to configure clock in
 Broadcom iProc mdio mux

On Wed, Aug 01, 2018 at 09:23:14PM +0100, Russell King - ARM Linux wrote:
> On Wed, Aug 01, 2018 at 10:07:12PM +0200, Andrew Lunn wrote:
> > You might want to consider adding clk_optional_get() and
> > devm_clk_optional_get().
> 
> I think there's attempts to add such APIs but I don't think it's
> trivial - it seems to require a _lot_ of discussion.
> 
> I think part of that is because of the quirky use of error codes.
> If you look at clk_get(), it calls __of_clk_get_by_name() which
> returns:
> 
>  -ENOENT if DT is disabled
>  -ENOENT if the device has no DT node
>  -EPROBE_DEFER if the lookup in DT succeeds but there's no registered
>    clock
>  -EINVAL if the device has a DT node but the lookup of the name
>    failed (in otherwords, the optional clock was omitted)
>  -ENOENT if the clocks = property has not enough clocks for the
>     clock-names property
>  -ENOMEM if we fail to allocate the clk
>  -ENOENT if __clk_get() fails

That makes it hard. I added phy_optional_get() early on, when the
error cases were simple. Hopefully they remain simple...

      Andrew