[PATCH v3 4/4] mmc: sdhci-esdhc-imx: add device tree probe support

On Thu, Jul 14, 2011 at 01:36:39AM +0900, Grant Likely wrote:
[...]

Only for irqs and regs.  gpios have never been automatically loaded
into resources.

Which doesn't mean we wouldn't want it sooner or later.

quoted

- Any pros for using named resources in the device tree? I don't
?see any.

Human readability.  To know exactly what a gpio is intended to be used
for.  Particularly for the case where a device might not use all the
gpios that it could use.  Yes, the gpios property can have 'holes' in
it, but the observation was made by several people that it is easy to
get wrong.  I for one thing the concern was well justified.

The GPIO bindings are no harder to deal with than PCI memory bindings,
not even close to that complexity. So I don't really see why you try
to simplify GPIOs, but disagree on making the same for memory and
interrupt resources.

For example arch/powerpc/boot/dts/ebony.dts, 'mcmal' node has five
interrupts (txeob, rxeob, serr, txde, rxde). Or, gianfar nodes have
either three interrupts (tx, rx, err) or just one.

The average user of 'gpios' has 1-2 entries (the noticeable exception
is USB FHCI, which has 8 GPIOs).

I.e., I don't see how GPIOs are special. I'm all for consistency,
that's it. If that doesn't work for IRQs, then I want to understand
why so. And if you explain why named resources are no good for IRQs,
maybe I could use the same argument against named GPIOs? :-)

Or it could be otherwise: we agree that named resources are good, and
we should explicitly write when to use named and when to use anonymous
resources.

quoted

So, I suggest to at least discuss this stuff a little bit more
before polluting device trees with dubious ideas.

It was discussed on list quite a while ago.

I probably wasn't Cc'ed, can you point me to that thread?

The last time I was Cc'ed on a such discussion, we (well who cared
enough to 'vote') agreed* that we should wait with deploying named
GPIOs scheme, and discuss it later. And here we are.

The patch that added of_get_named_gpio() triggered no discussion
at all, but I wasn't Cc'ed either.

* http://lists.ozlabs.org/pipermail/linuxppc-dev/2008-October/064701.html

-- 
Anton Vorontsov
Email: cbouatmailru at gmail.com