Re: [RFC PATCH 11/11] ARM: DT: Add support to system control module for OMAP4

[Konstantin Baydarov <kbaidarov@dev.rtsoft.ru>]

  Hi.
On 05/30/2012 01:26 PM, Cousson, Benoit wrote:
> On 5/30/2012 11:05 AM, Konstantin Baydarov wrote:
>> On 05/30/2012 12:38 PM, Cousson, Benoit wrote:
>>> On 5/29/2012 11:49 AM, Konstantin Baydarov wrote:
>>>> Hi, Eduardo.
>>>>
>>>> On 05/25/2012 12:26 PM, Eduardo Valentin wrote:
>>>>> This patch add device tree entries on OMAP4 based boards for
>>>>> System Control Module (SCM).
>
> ...
>
>>>> I believe that CPU-specific bandgap definition should be moved to
>>>> bard specific dts.
>>>
>>> Mmm, why, since it is CPU specific and not board specific. I has to
>>> be in the SoC file.
>> Speaking about omap4430 - omap4430 bandgap differs from omap4460, so
>> if omap4430 bandgap support will be added to omap-bandgap driver the
>> version of bandgap should specified in dts file. omap4.dtsi is a
>> common for omap4 boards, that is why I'm suggesting to move bandgap
>> description to probably board specific file.
>
> OK, I got your point, but in that case we could potentially define a omap4460.dtsi file.
>
>> Another solution is to
>> determine bandgap type in driver probe function, but in that case
>> "ti,omap4460-bandgap" in omap4.dtsi should be replaced to
>> "ti,omap4-bandgap".
>
> Yes, this is the best solution, but that assume that we can identify the control module version from the HW, which is not necessarily true :-(
>
> The IP_REVISION (offset = 0) value are unfortunately not documented, so we should read it to check if they are different from omap4430 and 4460.
>
> The bitfield layout in that register is:
>
> IP_REV_MAJOR: 8..10
> IP_REV_CUSTOM: 6..7
> IP_REV_MINOR: 0..5
Probably, cpu_is_omap443x() and cpu_is_omap446x() can be used in bandgap driver probe function. Actually many drivers use cpu_is_omap*():
drivers/mfd/omap-usb-host.c
drivers/mfd/twl-core.c

  BR,
    Konstantin Baydarov.

>
> Regards,
> Benoit