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

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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?

Thanks,
Archit


+ADV7533 specific supplies:
+- a2vdd-supply: 1.8V supply that powers up the A2VDD pin on the chip.
+- v1p2-supply: A supply that powers up the V1P2 pin on the chip. It can
be
+  either 1.2V or 1.8V.

  Required nodes:


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