Re: [PATCHv2 1/3] Add support for GMT G762/G763 PWM fan controller

[Guenter Roeck <linux@roeck-us.net>]

On Sun, Jun 02, 2013 at 05:45:58PM +0200, Arnaud Ebalard wrote:
> Hi,
> 
> >> I haven't noticed this issue while testing your v1 patch series because
> >> at the time I was using a board with an U-Boot modified by LaCie. This
> >> last sets the set_cnt register to 0 while U-Boot mainline don't.
> >> Actually, the 2Big fan is not configured nor even started by U-Boot
> >> mainline. I have to fix this but maybe that something can be done in
> >> the g762 Linux driver too ?
> 
> At the moment, DT bindings and platform_data structure both allow
> setting an initial fan_target value. I could add a 'pwm' binding for DT  
> and an assoicated field in platform_data to allow passing an initial
> value so that maintainers of platforms with a 2 wire fan (open loop) can
> still make the fan somewhat rotate at boot.
> 
Devicetree properties are supposed to describe the system, not its configuration.
There are exceptions, but I don't recall seeing a case where a parameter
can be set both with devicetree properties and sysfs attributes.

Before going further on this, we will need to have an ack from devicetree
maintainers which specifically permits your dual-configuration approach.
Even with that, you'll still have convince me that you need both (while
so far no other driver needed it).

Thanks,
Guenter