Re: [PATCH 1/7] mmc: dw_mmc: lookup for optional biu and ciu clocks

From: Russell King - ARM Linux
Date: Thu May 10 2012 - 09:44:08 EST


On Wed, May 02, 2012 at 03:53:53PM +0100, James Hogan wrote:
> Hi
>
> On 2 May 2012 06:07, Thomas Abraham <thomas.abraham@xxxxxxxxxx> wrote:
> > +       if (IS_ERR(host->biu_clk))
> > +               dev_info(&host->dev, "biu clock not available\n");
>
> In this case, should it set host->biu_clk to NULL or are clk_disable
> and clk_put guaranteed to handle an IS_ERR value?

I keep saying this. NULL must be treated as a valid reutrn value from
clk_get() and must not use this as a sentinel. The clk namespace is
that errors are indicated with IS_ERR(clk) returning true. Everything
else must be assumed to be valid by drivers.
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