[PATCH 01/10] Add a common struct clk

Tony Lindgren
2011-04-29T10:58:33Z

* Thomas Gleixner <tglx@linutronix.de> [110429 03:42]:
> On Fri, 29 Apr 2011, Russell King - ARM Linux wrote:
>
> > On Thu, Apr 21, 2011 at 09:48:28PM +0200, Thomas Gleixner wrote:
> > > On Fri, 15 Apr 2011, Sascha Hauer wrote:
> > > > From: Jeremy Kerr <jeremy.kerr@canonical.com>
> > > > + * @get: Called by the core clock code when a device driver acquires a
> > > > + * clock via clk_get(). Optional.
> > > > + *
> > > > + * @put: Called by the core clock code when a devices driver releases a
> > > > + * clock via clk_put(). Optional.
> > >
> > > These callbacks are completely pointless. There are only two non empty
> > > implementations in tree:
> > >
> > > One does a try_module_get(clk->owner), which should be done in generic
> > > code. The other does special clock enabling magic which wants to go to
> > > clk->prepare().
> >
> > I disagree. Most clocks don't live in a module - there's only one
> > platform which does at present. To force every clock to have an owner
> > field is rediculous. We already know that the OMAP tree represents a
>
> So we trade an owner field (which can be NULL) versus two function
> pointers in the clk_ops struct, which are of course subject to be
> abused for all kind of crap which does not belong there at all.
>
> > significant amount of data, and for every additional unnecessary word,
> > it gobbles up another 4K of data space.
>
> What are we talking about?
>
> arch/arm/mach-omap2/clock2420_data.c:117
> arch/arm/mach-omap2/clock2430_data.c:126
> arch/arm/mach-omap2/clock3xxx_data.c:235
> arch/arm/mach-omap2/clock44xx_data.c:228
>
> So even if we could build a common kernel for all these omaps, then
> adding owner to struct clk will consume ~2800 bytes.

Just to correct something, we are already building a common kernel
for all these, see omap2plus_defconfig.

For the size, device tree will shrink down that data where only
only one set of clock data is passed to the kernel. So I don't
think the size is such a big issue.

Regards,

Tony