[U-Boot] [PATCH v3 00/54] dm: Introduce new driver model uclasses

[Jagan Teki]

On 1 July 2015 at 02:38, Simon Glass <sjg at chromium.org> wrote:
> Hi Tom,
>
> On 30 June 2015 at 14:31, Tom Rini <trini at konsulko.com> wrote:
>> On Tue, Jun 30, 2015 at 01:10:45PM -0700, York Sun wrote:
>>>
>>>
>>> On 06/30/2015 12:01 PM, Tom Rini wrote:
>>> > On Tue, Jun 30, 2015 at 11:42:41AM -0700, York Sun wrote:
>>> >>
>>> >>
>>> >> On 06/30/2015 11:33 AM, Simon Glass wrote:
>>> >>> Hi York,
>>> >>>
>>> >>> On 30 June 2015 at 10:08, York Sun <yorksun at freescale.com> wrote:
>>> >>>> Simon,
>>> >>>>
>>> >>>> Does the dm force using device tree? I was reviewing a patch set regarding SPI
>>> >>>> and found OF_CONTROL has to be selected in order to get the driver model happy.
>>> >>>>
>>> >>>> My understanding of the driver model is both device tree and platform data are
>>> >>>> allowed, like Linux. Is that still true?
>>> >>>
>>> >>> For buses you need device tree. I was rather hoping that we could
>>> >>> avoid platform data on platforms that have device tree. What is the
>>> >>> point?
>>> >>>
>>> >>
>>> >> Simon,
>>> >>
>>> >> It happens on a platform not using device tree, but DM will be used.
>>> >>
>>> >> I prefer DM to have both, rather than being forced to use device tree, unless we
>>> >> are going to enforce using device tree on all new platforms. Since device tree
>>> >> is still an option, I feel it is best to support platform data, like Linux
>>> >> drivers do.
>>> >
>>> > Well, to what end?  My recollection is that in short, the kernel has
>>> > both since platform data predates device tree (and converting platform
>>> > data to device tree is still a thing that happens).  But we're trying to
>>> > skip that intermediate step.  Are there platforms where you do not plan
>>> > to use a device tree, ever?

My observations with this approach (dm-spi)

1. We're planning to move spi driver with dm support but many of the
boards which
    used spi drivers don't have dts support yet.
2. I think dm will progress only when dts support progresses.

The only solution for this - if we need to move any driver to dm then check for
dts on particular board this driver uses and move that board to have
dts support.

Any comments?

>>> >
>>>
>>> Tom,
>>>
>>> I am not against using device tree at all. It is more dynamic and flexible. But
>>> I don't see any indication that we favor device tree over pdata (except in the
>>> code). If we are skipping pdata for new drivers, a clear message will be
>>> helpful. That's what I am trying to get clarification.
>>
>> OK.  I think we'd agreed to that at ELC-E last year and it might have
>> been in a few here-and-there emails but it's worth spelling out
>> somewhere.
>>
>> Hey Simon?  doc/driver-model/README.txt has a pdata example, so maybe
>> the answer here is it's time to update README.txt in a few ways :)
>
> I'll prepare a patch.

thanks!
-- 
Jagan | openedev.