Re: [PATCH 6/7] mfd: cros_ec: Instantiate sub-devices from device tree

[Javier Martinez Canillas <javier.martinez@collabora.co.uk>]

Hello Andreas,

On 07/29/2014 02:34 PM, Andreas Färber wrote:
> Hi Javier,
> 
> Am 28.07.2014 14:19, schrieb Javier Martinez Canillas:
>> From: Todd Broch <tbroch@chromium.org>
>> 
>> If the EC device tree node has sub-nodes, try to instantiate them as
>> MFD sub-devices.  We can configure the EC features provided by the board.
>> 
>> Signed-off-by: Todd Broch <tbroch@chromium.org>
> 
> This is provoking the blunt question: What sub-devices is it good for?
> I.e., do you have a matching DT patchset that adds such devices?
> 

For Peach Pit and Pi, the matching DTS changes is [0]. But answering your
question it is to instantiate the subdevices that can be child nodes of either
cros-ec-spi or cros-ec-i2c. So for the devices that are directly connected to
the EC Cortex-M through i2c.

> In particular I'm wondering whether that would help with the tps65090 on
> Spring? It's a "power-regulator" sub-node of cros-ec in 3.8.
> 

Spring is a little more complicated since the EC in Spring don't have the full
EC_CMD_I2C_PASSTHRU. So the downstream Chrome OS 3.8 kernel has a forked
tps65090 driver (drivers/regulator/cros_ec-tps65090.c) that talks directly with
the cros_ec MFD driver, you can get more info from [1] in the "About Spring"
section.

> Thanks,
> Andreas
> 

Best regards,
Javier

[0]:
https://git.kernel.org/cgit/linux/kernel/git/kgene/linux-samsung.git/commit/?h=for-next&id=8060098bbb564d27a287057a93d4fe3bfd266290
[1]: http://code.google.com/p/chromium/issues/detail?id=391797