Re: [PATCH v2 1/4] dt-bindings: drm/bridge: adv7511: Add regulator bindings

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On Fri, Oct 14, 2016 at 12:40 AM, Archit Taneja <architt@xxxxxxxxxxxxxx> wrote:
> Hi Rob,
>
>
> On 09/26/2016 01:42 PM, Laurent Pinchart wrote:
>>
>> Hi Archit,
>>
>> On Monday 26 Sep 2016 12:10:11 Archit Taneja wrote:
>>>
>>> On 9/25/2016 10:58 PM, Laurent Pinchart wrote:
>>>>
>>>> On Friday 23 Sep 2016 14:50:27 Archit Taneja wrote:
>>>>>
>>>>> Add the regulator supply properties needed by ADV7511 and ADV7533. The
>>>>> regulator names are named after the pin names, except for DVDD_3V on
>>>>> ADV7511, which is left v3p3 to have the same name as it's on ADV7533.
>>>>>
>>>>> ADV7511 has a BGVDD pin for which the voltage to be configured isn't
>>>>> clear. This needs to be updated in the document later.
>>>>>
>>>>> The regulators are specified as optional properties since there can
>>>>> be boards which have a fixed supply directly routed to the pins, and
>>>>> these may not be modelled as regulator supplies.
>>>>>
>>>>> Cc: Rob Herring <robh@xxxxxxxxxx>
>>>>> Cc: devicetree@xxxxxxxxxxxxxxx
>>>>> Signed-off-by: Archit Taneja <architt@xxxxxxxxxxxxxx>
>>>>> ---
>>>>> v2:
>>>>> - Specify regulator supplies for ADV7511 too.
>>>>> - Have separate supply entries for AVDD, DVDD, PVDD, A2VDD pins.
>>>>> - Add additional BGVDD supply for ADV7511.
>>>>>
>>>>>   .../devicetree/bindings/display/bridge/adi,adv7511.txt     | 14
>>>>> +++++++
>>>>>   1 file changed, 14 insertions(+)
>>>>>
>>>>> diff --git
>>>>> a/Documentation/devicetree/bindings/display/bridge/adi,adv7511.txt
>>>>> b/Documentation/devicetree/bindings/display/bridge/adi,adv7511.txt
>>>>> index
>>>>> 6532a59..66e6bae 100644
>>>>> --- a/Documentation/devicetree/bindings/display/bridge/adi,adv7511.txt
>>>>> +++ b/Documentation/devicetree/bindings/display/bridge/adi,adv7511.txt
>>>>>
>>>>> @@ -56,6 +56,20 @@ Optional properties:
>>>>>   - adi,disable-timing-generator: Only for ADV7533. Disables the
>>>>> internal
>>>>>
>>>>> timing generator. The chip will rely on the sync signals in the DSI
>>>>> data
>>>>> lanes, rather than generate its own timings for HDMI output.
>>>>> +- avdd-supply: A 1.8V supply that powers up the AVDD pin on the chip.
>>>>> +- dvdd-supply: A 1.8V supply that powers up the DVDD pin on the chip.
>>>>> +- pvdd-supply: A 1.8V supply that powers up the PVDD pin on the chip.
>>>>> +- v3p3-supply: A 3.3V supply that powers up the pin called DVDD_3V on
>>>>> +  ADV7511 and V3P3 on ADV7533.
>>>>> +
>>>>> +ADV7511 specific supplies:
>>>>> +- bgvdd-supply: Powers the BGVDD pin. The voltage isn't clear from
>>>>> +  available datasheets.
>>>>
>>>>
>>>> It's a 1.8V supply. The ADV7511 hardware user's guide recommends tying
>>>> it
>>>> to the PVDD supply, so I'm not sure we need a separate supply in DT.
>>>
>>>
>>> Thanks for providing the info. I'll update it in the doc.
>>>
>>>> Similarly, the user's guide recommends supplying the AVDD, DVDD and PVDD
>>>> pins with a single 1.8V LDO and three independent filters. We could thus
>>>> possibly combine them into a single 1.8V supply.
>>>
>>>
>>> I'd originally specified only one AVDD supply for all the 1.8 V
>>> supplies, but Rob had recommended using separate supplies for each pin.
>>>
>>> I guess it doesn't do much harm specifying separate supplies, a
>>> board can just provide avdd-supply, and the rest would be assumed dummy.
>>
>>
>> DT should use the same regulator phandle for all power supplies in that
>> case,
>> not specify a single one.
>>
>>> It could also help describe boards which may not have followed the
>>> user guide's recommendation, but I agree that's probably a rare
>>> scenario.
>>>
>>> Is it okay if we stick with multiple supplies as it is in this version?
>>
>>
>> It seems overkill to me but I can live with that. I'd remove the bgvdd
>> supply
>> though.
>>
>> Rob, what's your opinion on this ? Is there a specific reason why you
>> prefer
>> splitting the 1.8V supply in one supply per pin, when the hardware user's
>> guide recommend powering them from the same LDO ?
>
>
> Could you suggest us which way to go?

If they are really intended to be the same supply, then combining them
is fine with me.

Rob
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