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Date: Thu, 20 Dec 2012 20:51:13 +0000
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Lee Jones <lee.jones@linaro.org>
Cc: Linus Walleij <linus.walleij@linaro.org>,
        Steve Glendinning <steve.glendinning@shawell.net>,
        Robert Marklund <robert.marklund@stericsson.com>,
        linus.walleij@stericsson.com, arnd@arndb.de, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 4/4] net/smsc911x: Provide common clock functionality
Message-ID: <20121220205113.GD14363@n2100.arm.linux.org.uk>
References: <1355937587-31730-1-git-send-email-lee.jones@linaro.org> <1355937587-31730-4-git-send-email-lee.jones@linaro.org> <CACRpkda79O_b3Z8g7Sy7vMtW9neZU4x-Z=iEQgjqu4X5tFKyhw@mail.gmail.com> <20121220192441.GC14363@n2100.arm.linux.org.uk> <20121220203514.GN2691@gmail.com>
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On Thu, Dec 20, 2012 at 08:35:14PM +0000, Lee Jones wrote:
> On Thu, 20 Dec 2012, Russell King - ARM Linux wrote:
> 
> > On Thu, Dec 20, 2012 at 08:12:08PM +0100, Linus Walleij wrote:
> > > On Wed, Dec 19, 2012 at 6:19 PM, Lee Jones <lee.jones@linaro.org> wrote:
> > > 
> > > > Some platforms provide clocks which require enabling before the
> > > > SMSC911x chip will power on. This patch uses the new common clk
> > > > framework to do just that. If no clock is provided, it will just
> > > > be ignored and the driver will continue to assume that no clock
> > > > is required for the chip to run successfully.
> > > >
> > > > Cc: Steve Glendinning <steve.glendinning@shawell.net>
> > > > Cc: netdev@vger.kernel.org
> > > > Signed-off-by: Lee Jones <lee.jones@linaro.org>
> > > 
> > > Seems to me like it'll do the trick.
> > > Acked-by: Linus Walleij <linus.walleij@linaro.org>
> > 
> > This looks fairly dangerous.  What about those platforms which use this
> > driver, but don't provide a clock for it?
> > 
> > It looks like this will result in those platforms losing their ethernet
> > support.  There's at least a bunch of the ARM evaluation boards which
> > make use of this driver...
> 
> Right, but nothing should regress. If no clock is provided the driver
> moves on during the request and will refuse to prepare, enable and
> disable there after. 
> 
> Unless I've made a mistake somewhere? If so, I'd be happy to fixup.

No, but... don't use NULL for that.  Use IS_ERR(pdata->clk) instead.