On Wed, Jul 9, 2014 at 11:18 PM, Bjorn Andersson [off-list ref] wrote:

On Wed, Jul 9, 2014 at 1:53 AM, Linus Walleij [off-list ref] wrote:

quoted

On Tue, Jul 8, 2014 at 3:26 AM, Bjorn Andersson
[off-list ref] wrote:

quoted

quoted

+The following generic properties as defined in pinctrl-bindings.txt are valid
+to specify in a pin configuration subnode:
+
+- pins:
+       Usage: required
+       Value type: <string-array>
+       Definition: List of gpio pins affected by the properties specified in
+                   this subnode.  Valid pins are:
+                       gpio1-gpio6 for pm8018
+                       gpio1-gpio12 for pm8038
+                       gpio1-gpio40 for pm8058
+                       gpio1-gpio38 for pm8917
+                       gpio1-gpio44 for pm8921

I usually name pins with CAPITAL LETTERS so would be
"GPIO1", "GPIO2" etc, lowercase may be confusing as these are
names not functions or groups.

I was hoping to be able to follow the pattern used in pinctrl-msm; can I say
something nice to have you agree on this? There's no difference between pins
and groups here.

That's OK.

quoted

quoted

+- function:
+       Usage: optional
+       Value type: <string>
+       Definition: Specify the alternative function to be configured for the
+                   specified pins.  Valid values are:
+                       "normal",
+                       "paired",
+                       "func1",
+                       "func2",
+                       "dtest1",
+                       "dtest2",
+                       "dtest3",
+                       "dtest4"

These are a bit ambigous, why doesn't the driver present functions that
are more specific than "func1", "func2"? Or "dtest1"?

I agree, unfortunately I have only seen traces of the actual function matrix;
for pm8xxx I have no documentation and for pm8x41 they are only listed as
func[1-2] and dtest[1-4].

Maybe if someone at Qualcomm could release such a list we could provide a
proper table instead.

I guess Stephen Boyd can help us. (?)

quoted

Isn't the type simply bool?

No, the property is bool but the actual value is void. But looking an extra
time in the epapr I see that it's supposed to be "empty" - so will update.

OK.

quoted

quoted

+- bias-pull-up:
+       Usage: optional
+       Value type: <u32> (optional)
+       Definition: The specified pins should be configued as pull up. An
+                   optional argument can be used to configure the strength.
+                   Valid values are; as defined in
+                   <dt-bindings/pinctrl/qcom,pm8xxx-gpio.h>:
+                   1: 30uA                     (PM8XXX_GPIO_PULL_UP_30)
+                   2: 1.5uA                    (PM8XXX_GPIO_PULL_UP_1P5)
+                   3: 31.5uA                   (PM8XXX_GPIO_PULL_UP_31P5)
+                   4: 1.5uA + 30uA boost       (PM8XXX_GPIO_PULL_UP_1P5_30)

Hm, I don't know of the internal kernel API or so, but I'm thinking that
for the DT bindings, this definition should be generic in
Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
and put in SI units like uA.

Totally agree with you; and this is already specified in pinctrl-binding.txt as
being Ohm.

So I first did a spin with the strength as a separate property, but as that
because the only part that pinconf-generic didn't parse for me I merged it and
wanted your comment on it.

Yeah. And thinking of it.... how can it be uA? It has to be Ohms... it's a pull
up resistor thing after all. I suspect the uA value is just something like the
maximum current drawn through the pullup given a certain voltage?

quoted

So I would prefer:

bias-pull-up = <30>;

Yeah, but that's the easy one ;)

How do you say 1.5 or 31.5 and how do you differ that from 1.5 + 30 boot?

It needs to be set using Ohms.

quoted

for 30 uA. Maybe we want nA even? I'm uncertain about the proper granularity
here :-/

Magic enumerators 1,2,3,4 doesn't seem so good, that seems more like it's
trying to match the magic value that is to be poked into a register or
something like that.

The stuff going into the hardware is a value 0-3 for pull up; so these values
are "only" an enum with the additional benefit of saying "bias-pull-up;"
results in 30uA pull up which is the most commonly used form (hence being
optional).

What is the nominal voltage of these pins? GIven that you can figure
out the Ohms. And I suspect it to be something very close to N times
the resistance of a depleted transistor in this technology.

quoted

quoted

+- drive-strength:
+       Usage: optional
+       Value type: <u32>
+       Definition: Selects the drive strength for the specified pins. Value
+                   drive strengths are:
+                       0: no   (PM8XXX_GPIO_STRENGTH_NO)
+                       1: high (PM8XXX_GPIO_STRENGTH_HIGH)
+                       2: medium       (PM8XXX_GPIO_STRENGTH_MED)
+                       3: low  (PM8XXX_GPIO_STRENGTH_LOW)

I would really prefer to have these in mA, because the genric pinconf
bindings say they should be! SI units are so much more understandable.

This is all the information to be found in the available documentation and
code. Maybe someone from Qualcomm can shed some light on it?

Stephen?

quoted

quoted

+                            <234 1>, <235 1>;

So this looks a bit weird. But if I just get to understand the hardware
I guess it won't anymore.

So there is an interrupt parent to which the IRQ lines from the PMIC
are routed back through external lines to IRQ offsets 192 thru 235?

The pm8921-core exposes 256 interrupts, the listed 44 interrupts here are what
comes out of that.

I get it. It makes sense to handle all IRQs in the core rather than spawning
yet another irqchip for the pin control driver.

I was really reluctant to list all the interrupts, but I think it turned out
nicer than any of my other attempts; like only providing a base and then
relying on interrupts being consecutive.

I agree.

Yours,
Linus Walleij