Messages in this thread | | | Date | Wed, 19 Dec 2012 19:08:24 +0000 | From | Russell King - ARM Linux <> | Subject | Re: Inconsistency in clk framework |
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On Thu, Dec 20, 2012 at 08:00:49AM +1300, Tony Prisk wrote: > On Thu, 2012-12-20 at 06:34 +1300, Tony Prisk wrote: > > On Wed, 2012-12-19 at 09:26 +0000, Russell King - ARM Linux wrote: > > > On Wed, Dec 19, 2012 at 05:10:33PM +1300, Tony Prisk wrote: > > > > Hi Mike, > > > > > > > > In attempting to remove some IS_ERR_OR_NULL references, it was pointed > > > > out that clk_get() can return NULL if CONFIG_HAVE_CLK is not defined. > > > > > > That is correct - but why is that a problem? As far as users are > > > concerned, NULL is a valid clock. If HAVE_CLK is undefined, do you > > > want all your drivers to suddenly stop working? > > > > That will be where the misunderstanding has occurred - I didn't consider > > NULL to be a valid clock. > > > > Given that NULL is a valid clock, I guess all tests against get_clk and > > of_get_clk results should be IS_ERR_OR_NULL. Correct? > > > For the sake of clarity, I should rephrase: > > If the driver can't operate with a NULL clk, it should use a > IS_ERR_OR_NULL test to test for failure, rather than IS_ERR.
Why should a _consumer_ of a clock care? It is _very_ important that people get this idea - to a consumer, the struct clk is just an opaque cookie. The fact that it appears to be a pointer does _not_ mean that the driver can do any kind of dereferencing on that pointer - it should never do so.
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