Re: [PATCH v6 1/4] Runtime Interpreted Power Sequences

On Thu, Sep 13, 2012 at 10:03:27AM +0300, Tomi Valkeinen wrote:

On Thu, 2012-09-13 at 09:00 +0200, Sascha Hauer wrote:

quoted

On Thu, Sep 13, 2012 at 09:54:09AM +0300, Tomi Valkeinen wrote:

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On Thu, 2012-09-13 at 15:36 +0900, Alex Courbot wrote:

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On Thursday 13 September 2012 14:22:57 Tomi Valkeinen wrote:
 

quoted

However, I fear these board specific things may be quite a bit anything,
so it may well be pwm, gpios and regulators are not enough for them. For
example, there could be an FPGA on the board which requires some
configuration to accomplish the task at hand. It could be rather
difficult to handle it with a generic power sequence.

Right. Note that this framework is supposed to be extended - I would like to 
at least add regulator voltage setting, and maybe even support for clocks and 
pinmux (but that might be out of place).

Yes, that's one concern of mine... I already can imagine someone
suggesting adding conditionals to the power sequence data. Perhaps also
direct memory read/writes so you can twiddle registers directly.

These memory writes can be avoided when these registers are abstracted
as a regular gpio/regulator/pwm driver.

quoted

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And so
on. Where's the limit what it should contain? Can we soon write full
drivers with the DT data? =)

I have this concern aswell, that's why I'm sceptical about this patch
set. But what are the alternatives? Adding power code to the drivers and
thus adding board specific code to them is backwards.

As was pointed out in earlier posts in this thread, these are almost
always device specific, not board specific.

Do you have examples of board specific power sequences or such?

Sure, tons of. One board needs a gpio to be set high to enable backlight,
the next one to low, a regulator has to be enabled, and to avoid
flickering a certain timing has to be ensured. This is all highly board
specific.

Sascha

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