[RFC PATCH 2/3] pinctrl: imx: add pinmux-imx53 support

On Tue, Dec 06, 2011 at 08:33:28AM +0100, Lothar Wa?mann wrote:

Hi,

Shawn Guo writes:

quoted

On Mon, Dec 05, 2011 at 10:18:38PM +0100, Sascha Hauer wrote:

quoted

Freescale has named the pins after their primary function which is quite
confusing.

The above means:

MX53_PATA_DATA8 -> mux mode 4
MX53_PATA_DATA9 -> mux mode 4
...

This brings me to the point that currently we have the pins described as

#define MX53_PAD_<name>__<function>

But that's also the reason why we have so many lengthy iomux-mx*.h on
imx.  Taking iomux-mx53.h for example, it's a 109K header with 1219
LOC, but probably only 10% of the definitions will actually be used.

Which has the benefit of having correct pin definitions for everyone
to use. If developers who need to use currently unused pindefs have to
create them on their own, there will always be a good chance in
getting them wrong.

If the configuration is not working, they will notice it's wrong anyway.

quoted

quoted

which means that you don't have to look into the datasheet to get the
different options for a pin

Looking at the datasheet when we write code is a pretty natural thing
to me.

The pindefs are like interrupt numbers or IO addresses for which there
also is a complete list of definitions in the kernel no matter whether
they are actually all in use.

The interrupt list is much shorter than iomux list here, which enumerate
every single function for every single pad.  Also, most interrupts stand
a pretty good chance to be used, while most of the pad functions do not.

-- 
Regards,
Shawn