Re: [PATCH RESEND 6/6] clk: s5p-g2d: Fix incorrect usage ofIS_ERR_OR_NULL

From: Russell King - ARM Linux
Date: Thu Jan 03 2013 - 05:00:15 EST

On Thu, Jan 03, 2013 at 12:05:20PM +0300, Dan Carpenter wrote:
> On Wed, Jan 02, 2013 at 06:31:53PM +1300, Tony Prisk wrote:
> > 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.
> >
> > Thread can be viewed here:
> >
> >
> Ah. Grand. Thanks...
> Btw. The documentation for clk_get() really should include some of
> this information.

It *does* contain this information. The problem is that driver authors
_ARE_ stupid, lazy morons who don't bother to read documentation.

* clk_get - lookup and obtain a reference to a clock producer.
* @dev: device for clock "consumer"
* @id: clock consumer ID
* Returns a struct clk corresponding to the clock producer, or
* valid IS_ERR() condition containing errno. The implementation
* uses @dev and @id to determine the clock consumer, and thereby
* the clock producer. (IOW, @id may be identical strings, but
* clk_get may return different clock producers depending on @dev.)
* Drivers must assume that the clock source is not enabled.
* clk_get should not be called from within interrupt context.

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