[PATCH] efikamx: reintroduce Genesi Efika MX Smarttop via device tree

By the way just as an example, a board with the following could be
configured on i.MX53 without touching any IOMUX settings at all
besides DDR (which would get done at boot rom time through the dcd);

* Keypad (KPP)
* 24-bit Parallel display on IPU DI0
* GPIO6&7 pins 22 through 31, GPIO4 10 through 14, and a couple others
* Parallel camera on CSI0
* NAND
* Certain configurations of Ethernet
* PATA
* SD1 and SD2
* ESAI audio
* EIM bus
* CLKIH CLKIL and CLKO clocks

With discrete power (no PMIC), bitbang I2C and SPI to control whatever
minimal peripherals you need out there, this is basically a Smarttop.
Sure, it's not as fun as using the real SPI, I2C buses and you don't
get a UART, but it's possible.

-- 
Matt Sealey [off-list ref]
Product Development Analyst, Genesi USA, Inc.


On Fri, Aug 10, 2012 at 9:26 AM, Matt Sealey [off-list ref] wrote:

On Fri, Aug 10, 2012 at 9:04 AM, Shawn Guo [off-list ref] wrote:

quoted

On Fri, Aug 10, 2012 at 08:36:02AM -0500, Matt Sealey wrote:

quoted

Requiring it breaks the entire concept of the device tree to describe running
hardware. It is not a configuration script. pinctrl should be optional
- built in
always, but not necessary to turn a board on if it's already configured.

How would kernel know if it's already configured, correctly?

Trust! When we release the new U-Boot, it will be already configured,
every pin in the schematic, every
pin from the old kernels (not mainline, some of that was wrong),
exactly the way it should be. There's
nothing new with the Efika MX.

If you try and boot it on the old Efika, it just won't work reliably
for any peripheral U-Boot didn't
already configure, but for the current version you'd get MMC, PATA,
serial port, SPI (NOR/PMIC)
which is all we configure in the DT right now anyway... this is only
going to be an issue once we
get to displays and USB (I2C isn't set up in the old one).

quoted

quoted

What would happen if a board were designed that only used the default ALT
settings on i.MX53 or so? You'd have to redefine every default IOMUX pad
just to get it to boot. That's intolerable.

Come on, even the pad configuration are all the default?  Even if that's
the case, yes, we still need to do it.  How do we know if firmware has
changed the settings or not.

TRUST...

Maybe you can't rely on the development boards from Freescale, but we have to
do unit testing at every stage of operation for consumer devices. Once U-Boot
passes all tests, why bother re-testing the exact same configuration, now done
twice, in the kernel? I don't want to debug pad settings twice, and we shouldn't
need to.

If you really think it's necessary then fine, we'll do it.

--
Matt Sealey [off-list ref]
Product Development Analyst, Genesi USA, Inc.