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Hi,
On 03/03/2014 10:33 AM, Maxime Ripard wrote:
> Hi Hans,
>
> On Sat, Feb 22, 2014 at 08:10:54PM +0100, Hans de Goede wrote:
>>>>> Since IIRC we have pretty much the same needs for the USB, can't we just
>>>>> drop the SATA specific mention and use it as the common DTSI for the
>>>>> usual regulators?
>>>>
>>>> On most boards with sata, there will also be 1 or 2 usb regulators, so we
>>>> need differently named regulator nodes for all 3 of ahci, usb1 and usb2
>>>> vbus. On some boards how ever we may only need the usb regulators.
>>>
>>> Yes, obviously...
>>>
>>>> So if you look in my current personal sunxi-devel tree you will see
>>>> separate dtsi files for both ahci and usb regulators,
>>>
>>> And this is precisely what I don't understand. Why do you *need* different
>>> DTSI files. If there's common regulators, that are used on most boards,
>>> fine, create a common regulators files. But why do you have to create a
>>> DTSI to define only one regulator.
>>>
>>>> another advantage of having these separate is that the gpio controlling
>>>> the regulator can be pre-populated with the reference design gpio which is
>>>> used in most boards, so that the ahci specific code in the dts becomes
>>>> only the ahci: sata@... node.
>>>
>>> I understand very well the advantages of what having a reference regulators
>>> bring. What I don't understand is the benefits of having "topics"
>>> regulators DTSI.
>>
>> Ok, so let me try to explain:
>>
>> With topics regulator files, the ahci bits look something like this for a
>> board using the reference design gpio:
>>
>> /include/ "sunxi-ahci-reg.dtsi"
>>
>> ...
>>
>> ahci: sata@01c18000 { target-supply = <®_ahci_5v>; status = "okay"; };
>>
>> If we put all regulators in one file, then the ahci regulator cannot be
>> enabled (so it will have status = "disabled) by default since most boards
>> don't have it, so things would change into:
>>
>> /include/ "sunxi-common-regulators.dtsi"
>>
>> ...
>>
>> ahci: sata@01c18000 { target-supply = <®_ahci_5v>; status = "okay"; };
>>
>> ...
>>
>> reg_ahci_5v: ahci-5v { status = "okay"; };
>>
>> Notice the addition of the 2nd node. This is why I ended up doing 2 separate
>> dtsi files for the ahci and for the usb regulators.
>>
>> To me saying:
>>
>> /include/ "sunxi-ahci-reg.dtsi"
>>
>> Makes it clear to the reader that the board has a ahci target-supply
>> regulator, so enabling it separately seems being overly verbose.
>>
>> Of course of we change it to:
>>
>> /include/ "sunxi-common-regulators.dtsi"
>>
>> Then the verbosity / explicit enabling of various regulators becomes a good
>> thing, as it is not directly clear what the include does.
>>
>> But if we do this, then for many boards we end up replacing:
>>
>> /include/ "sunxi-ahci-reg.dtsi" /include/ "sun4i-a10-usb-vbus-reg.dtsi"
>>
>> With:
>>
>> /include/ "sunxi-common-regulators.dtsi"
>>
>> reg_ahci_5v: ahci-5v { status = "okay"; };
>>
>> reg_usb1_vbus: usb1-vbus { status = "okay"; };
>>
>> reg_usb2_vbus: usb2-vbus { status = "okay"; };
>>
>> I prefer the shorter version, but I can completely understand if you prefer
>> the slightly more verbose version, this would also get rid of having
>> different usb regulator dtsi files for sun4i / sun5i (as sun5i only has 1
>> usb host).
>>
>> I hope this helps explain my reasoning, as said I'm fine with either way, if
>> you want to change over to a single file + explicit enabling, let me know
>> and I'll respin the ahci dts patches. Note I'm going on vacation for a week
>> starting Monday, so you likely won't get a new version until next weekend.
>
> Yes, I strongly prefer the second case. That allows to have a good-enough
> degree of factorisation, while not having anything happening behind the
> scenes.
Good, note I've already assumed as much and send a new series
which already has moved over to 1 common regulators dtsi,
with all regulators disabled by default + explicit enabling
in the board dts files.
Regards,
Hans
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