[U-Boot] twl4030_power_init cleanup proposal

[U-Boot] twl4030_power_init cleanup proposal

[Grazvydas Ignotas]

hi,

drivers/power/twl4030.c has a twl4030_power_init() function which is
called by most (all?) OMAP3 boards. What it does is enabling VAUX3,
VPLL2 and VDAC power supplies in TWL4030/TPS659x0 chip. However they
are all very board specific and in most cases not needed at all, at
least for booting the kernel. They also cause regulator warnings on
latest kernels.

VAUX3: board specific, beagle doesn't have it connected at all, so it
wastes power there.
VPLL2: board specific, typically display related, as mainline u-boot
shows no graphics I think it can be removed.
VDAC: typically used to power TV-out DACs, can be removed. VDAC and
VPLL2 is already handled by kernel by DSS2.

So I think VDAC, VPLL2 can be safely removed, probably VAUX3 too with
whole twl4030_power_init().

Gra?vydas

[U-Boot] twl4030_power_init cleanup proposal

[Tom]

Grazvydas Ignotas wrote:
> hi,
> 
> drivers/power/twl4030.c has a twl4030_power_init() function which is
> called by most (all?) OMAP3 boards. What it does is enabling VAUX3,
> VPLL2 and VDAC power supplies in TWL4030/TPS659x0 chip. However they
> are all very board specific and in most cases not needed at all, at
> least for booting the kernel. They also cause regulator warnings on
> latest kernels.
> 
> VAUX3: board specific, beagle doesn't have it connected at all, so it
> wastes power there.
> VPLL2: board specific, typically display related, as mainline u-boot
> shows no graphics I think it can be removed.
> VDAC: typically used to power TV-out DACs, can be removed. VDAC and
> VPLL2 is already handled by kernel by DSS2.
> 
> So I think VDAC, VPLL2 can be safely removed, probably VAUX3 too with
> whole twl4030_power_init().
> 
> Gra?vydas

Please provide specifics on the kernel warnings.
These should be addressed.

The power setting should be done on board by board basis.
If you are concerned about beagle, please provide a beagle specific
patch.

Tom

[U-Boot] twl4030_power_init cleanup proposal

[Grazvydas Ignotas]

On Mon, Nov 30, 2009 at 6:17 PM, Tom <Tom.Rix@windriver.com> wrote:
> Grazvydas Ignotas wrote:
>>
>> hi,
>>
>> drivers/power/twl4030.c has a twl4030_power_init() function which is
>> called by most (all?) OMAP3 boards. What it does is enabling VAUX3,
>> VPLL2 and VDAC power supplies in TWL4030/TPS659x0 chip. However they
>> are all very board specific and in most cases not needed at all, at
>> least for booting the kernel. They also cause regulator warnings on
>> latest kernels.
>>
>> VAUX3: board specific, beagle doesn't have it connected at all, so it
>> wastes power there.
>> VPLL2: board specific, typically display related, as mainline u-boot
>> shows no graphics I think it can be removed.
>> VDAC: typically used to power TV-out DACs, can be removed. VDAC and
>> VPLL2 is already handled by kernel by DSS2.
>>
>> So I think VDAC, VPLL2 can be safely removed, probably VAUX3 too with
>> whole twl4030_power_init().
>>
>> Gra?vydas
>
> Please provide specifics on the kernel warnings.
> These should be addressed.

regulator_init_complete: incomplete constraints, leaving VDAC on

This can be fixed in kernel itself by declaring regulators as
"boot_on" or "always_on", but I think it's better just to not turn
them on when they are not needed.

> The power setting should be done on board by board basis.
> If you are concerned about beagle, please provide a beagle specific
> patch.

ok will do that for pandora, as that's the hardware I have.

Gra?vydas