Re: [PATCH v2 2/2] arm: dts: add support for AM437x StarterKit

On 06/18/2014 10:05 PM, Felipe Balbi wrote:

Hi,

On Wed, Jun 18, 2014 at 09:26:01PM -0500, Nishanth Menon wrote:

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On 06/18/2014 06:19 PM, Felipe Balbi wrote:
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Add support for TI's AM437x StarterKit Evaluation
Module.

is there a link for this platform?

internal only

but will eventually be sold externally? I assume this is not an TI

probably, but there's nothing public yet.

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internal only board.

correct assumption for all I know.

Yikes.. ok.. I'd let Tony et.al make the call on this, I guess.

would we really block a DTS just because there's no public wiki page
available (yet) ?

Sounds a bit extreme to me.

If this is an TI internal board without anyone outside that a few
select developers being able to get and work on it... I am a bit
skeptical on upstream kernel support and burden for forseeable future
in ensuring it is tested and continually maintained. if it an
one-off.. maybe fork might be good enough.. upstream not too attractive.

I mean, if it is targeted to be sold eventually, I have no objections
or blocks - just make it clear in commit message. I can imagine folks
wondering what the heck this is and googling without results(just like
I did).

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+	cd-gpios = <&gpio0 6 GPIO_ACTIVE_HIGH>;
+};
+
+&usb2_phy1 {
+	status = "okay";
+};
+
+&usb1 {
+	dr_mode = "peripheral";
+	status = "okay";
+};
+
+&usb2_phy2 {
+	status = "okay";
+};
+
+&usb2 {
+	dr_mode = "host";
+	status = "okay";
+};

none of the above need pinctrl? no regulator supplies?

pins in default states, drivers don't use regulators.

USB works without a supply? even a fixed voltage supply? that is
weird.

take a look at the minicom output I posted if you don't believe. Well,
to be exact, tps63010 [1] is the one which generates the regulated V5_0D
which is used as VBUS_USB. The enable pin in that device is tied to the
3v3 rail (dcdc4 regulator in the PMIC as most everything else) but
there's no way (otherwise) to control that thing. There's no control
bus, no way to write a driver.

Since the board will anyways turn off if you disable the 3v3 rail, it's
pretty much pointless to figure out a hack just to add this to DTS.

[1] http://www.ti.com/product/TPS63010

I am sure to trust you on the test log :) ->  but then from dts description
perspective, it is good if we describe the supplies, even as a always on
fixed-regulator. We had instances like 2430SDP ethernet where... umm... we
originally missed describing ethernet supply and boom, one fine morning, no
more nfs filesystem - I mean, it is a one off scenario there, but describing
regulators helps us atleast understand the power tree of the board a little
better.

Again, no strong opinions on my side, it is a good thing to do is all
I feel about it.

you mean something like:

	V5_0D: fixedregulator@0 {
		compatible = "regulator-fixed";
		regulator-name = "V5_0D";
		regulator-min-microvolt = <5000000>;
		regulator-max-microvolt = <5000000>;
		regulator-boot-on;
		regulator-always-on;
		vin-supply = <&dcdc4>;
	};

	VBUS_USB: fixedregulator@1 {
		compatible = "regulator-fixed";
		regulator-name = "VBUS_USB";
		regulator-min-microvolt = <5000000>;
		regulator-max-microvolt = <5000000>;
		regulator-boot-on;
		regulator-always-on;
		vin-supply = <&V5_0D>;
	};

I can add that, but note that it's *solely* to make sysfs look nice. And
if that's the case, most likely *every* DTS file in tree today as
incomplete. OTOH, I really consider this to be hugely unnecessary
because of the fact that board will turn off if 3v3 (dcdc4) is disabled.

Yes - something along those lines - Again, no strong opinions on my
side for these - just that it is a good thing to model in and may help
drivers where can use the awareness.

Regards,
Nishanth Menon
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