Nokia N900: twl4030-power different data in DTS and board code

Nokia N900: twl4030-power different data in DTS and board code

[Pali Rohár]

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Hello,

now I'm looking at differences between legacy board code and DTS file
for Nokia N900 and I see some inconsistency for twl4030-power driver.

In board code are defined more twl4030 power scripts which override
defaults defined in twl4030-power code. See:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/arm/mach-omap2/board-rx51-peripherals.c#n790

Next in DTS file is defined just "compatible" keyword, but no custom
scripts, see:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/omap3-n900.dts#n416

And the last in DTS file is defined line:

compatible = "ti,twl4030-power-n900" 

which is not in twl4030-power driver itself, see:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/mfd/twl4030-power.c#n851

So all this stuff looks like some errors when board code was ported to
DTS. Tony, can you look at this at all?

-- 
Pali Rohár
pali.rohar@gmail.com

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Re: Nokia N900: twl4030-power different data in DTS and board code

[Tony Lindgren]

* Pali Rohár <pali.rohar@gmail.com> [160102 06:14]:
> Hello,
> 
> now I'm looking at differences between legacy board code and DTS file
> for Nokia N900 and I see some inconsistency for twl4030-power driver.
> 
> In board code are defined more twl4030 power scripts which override
> defaults defined in twl4030-power code. See:
> 
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/arm/mach-omap2/board-rx51-peripherals.c#n790
> 
> Next in DTS file is defined just "compatible" keyword, but no custom
> scripts, see:
> 
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/omap3-n900.dts#n416
> 
> And the last in DTS file is defined line:
> 
> compatible = "ti,twl4030-power-n900" 
> 
> which is not in twl4030-power driver itself, see:
> 
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/mfd/twl4030-power.c#n851
> 
> So all this stuff looks like some errors when board code was ported to
> DTS. Tony, can you look at this at all?

AFAIK it should work fine with the generic "ti,twl4030-power-idle-osc-off".
This means reboot works and regulators are cut off during off mode.

The n900 specific code was based on something before the TI generic values
were available I think. And the last time I looked at it I came to the
conclusion the n900 specific code is no better.

Or did I miss something? Are you seeing some issues with PM with dts based
code?

We can certainly add it to twl4030-power if it provides something that
the "ti,twl4030-power-idle-osc-off" does not.

Regards,

Tony

Re: Nokia N900: twl4030-power different data in DTS and board code

[Pali Rohár]

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On Saturday 02 January 2016 18:14:31 Tony Lindgren wrote:
> * Pali Rohár <pali.rohar@gmail.com> [160102 06:14]:
> > Hello,
> > 
> > now I'm looking at differences between legacy board code and DTS
> > file for Nokia N900 and I see some inconsistency for twl4030-power
> > driver.
> > 
> > In board code are defined more twl4030 power scripts which override
> > defaults defined in twl4030-power code. See:
> > 
> > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tre
> > e/arch/arm/mach-omap2/board-rx51-peripherals.c#n790
> > 
> > Next in DTS file is defined just "compatible" keyword, but no
> > custom scripts, see:
> > 
> > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tre
> > e/arch/arm/boot/dts/omap3-n900.dts#n416
> > 
> > And the last in DTS file is defined line:
> > 
> > compatible = "ti,twl4030-power-n900"
> > 
> > which is not in twl4030-power driver itself, see:
> > 
> > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tre
> > e/drivers/mfd/twl4030-power.c#n851
> > 
> > So all this stuff looks like some errors when board code was ported
> > to DTS. Tony, can you look at this at all?
> 
> AFAIK it should work fine with the generic
> "ti,twl4030-power-idle-osc-off". This means reboot works and
> regulators are cut off during off mode.

Ok.

> The n900 specific code was based on something before the TI generic
> values were available I think. And the last time I looked at it I
> came to the conclusion the n900 specific code is no better.

Hm... if generic values are better, why old values are still there (in 
board n900 code)?

> Or did I miss something? Are you seeing some issues with PM with dts
> based code?

I'm just asking why we have different code for DST and board...

> We can certainly add it to twl4030-power if it provides something
> that the "ti,twl4030-power-idle-osc-off" does not.

But do we need 'compatible = "ti,twl4030-power-n900"' specification in 
omap3-n900.dts file at all?

-- 
Pali Rohár
pali.rohar@gmail.com

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Re: Nokia N900: twl4030-power different data in DTS and board code

[Tony Lindgren]

* Pali Rohár <pali.rohar@gmail.com> [160102 13:39]:
> On Saturday 02 January 2016 18:14:31 Tony Lindgren wrote:
> 
> > The n900 specific code was based on something before the TI generic
> > values were available I think. And the last time I looked at it I
> > came to the conclusion the n900 specific code is no better.
> 
> Hm... if generic values are better, why old values are still there (in 
> board n900 code)?

We never had PM working in a generic way for the legacy booting but
relied on board specific configuration instead for the ones that did
work. Probably not worth changing the board-*.c file configuration
unless you want to test that the new generic settings work.

> > Or did I miss something? Are you seeing some issues with PM with dts
> > based code?
> 
> I'm just asking why we have different code for DST and board...

OK. Yeah no reason beyond somebody taking the time to verify that the
generic settings work on n900 in legacy booting mode :)

> > We can certainly add it to twl4030-power if it provides something
> > that the "ti,twl4030-power-idle-osc-off" does not.
> 
> But do we need 'compatible = "ti,twl4030-power-n900"' specification in 
> omap3-n900.dts file at all?

Well that generally done to allow adding support for the board specific
configuration if needed with a fallback to the generic configuration.
That's used quite a bit, for example boards typically set the compatible
to the specific board but still end up booting with a generic one
sucha as "ti,omap3".

Regards,

Tony