Re: [PATCHv2 1/4] ARM: dts: meson8b: odroidc1: Add usb phy power node

Hi Anand,

On Sun, Jul 18, 2021 at 5:38 AM Anand Moon [off-list ref] wrote:
[...]

quoted

quoted

enable input power to USB ports, set it to Active Low.

[    1.253149] phy phy-c1108820.phy.0: Looking up phy-supply from device tree
[    1.253166] phy phy-c1108820.phy.0: Looking up phy-supply property
                in node /soc/cbus@c1100000/phy@8820 failed

high prio:
Can you please describe how I can test this patch?
My concern is that previously I have tested your patch with ACTIVE_LOW
and ACTIVE_HIGH polarity.
In both cases USB is working and I cannot observe any change (apart
from this debug message being gone).

In the Odroid-C1 schematics (page 1) GPIOAO.BIT5 is connected to USB_OTG *only*.
I cannot give my Acked-/Reviewed-/Tested-by without a description of
how I can actually test the GPIO potion of this patch.

This question is still open.
Even with all your explanations below I am missing a way to verify if
GPIOAO_5 is the correct GPIO to use.

quoted

[...]

quoted

+               /*
+                * signal name from schematics: PWREN - GPIOAO.BIT5
+                */
+               gpios = <&gpio_ao GPIOAO_5 GPIO_ACTIVE_HIGH>;

low prio:
Even though it's strictly not necessary I think this is confusing to read.
Since there's no "enable-active-high" property the GPIO will be
considered as "active low".
My suggestion is to change GPIO_ACTIVE_HIGH to GPIO_ACTIVE_LOW

My apologies, I might have sent the wrong set of patches its
GPIO_ACTIVE_LOW I meant
I have formatted with and in the course of testing and verifying It
might have got SKIPPED.
I didn't do this intentionally it happen with a mistake with my two
repositories.
I don't intend to repeat my mistake, again and again, *sorry for the trouble*.

no worries, that's why I mentioned that it's low priority

quoted

Also if you have any extra information since you last pinged me on IRC
then it would be great if you could document it.
I am referring to these IRC message, where you are stating that the
correct polarity should be "active high":
<armoon> xdarklight I have a question on USB GPIO Polarity on Odroid C1+

 > <armoon> As per the

quoted

https://dn.odroid.com/S805/Schematics/odroid-c1+_rev0.4_20160226.pdf
<armoon> MP62551DGT-LF IC controls the power for the USB PORTS
<armoon> https://www.mouser.com/datasheet/2/277/MP62550-1384050.pdf is
MP62551DGT datasheet
<armoon> As per the data sheet in section ORDERING INFORMATION  Active
enable signal is set below MP62551DGT Active High

[1] https://www.mouser.com/datasheet/2/277/MP62550-1384050.pdf

I have read the datasheets MP62551DGT EN*  pin its Enable input. Active Low:
       *EN I Enable input. Active Low: (MP62550), Active High: (MP62551).*

I have tested with ACTIVE_LOW and followed all the steps invalidating
 this with debugfs output.

Last login: Tue Jul 13 00:02:49 2021 from 10.0.0.14
[alarm@archl-c1e ~]$ sudo cat /sys/kernel/debug/gpio | grep usb
 gpio-1953 (USB_HUB_RST_N       |usb-hub-reset       ) out hi
 gpio-1954 (USB_OTG_PWREN       |regulator-usb-pwr-en) out lo ACTIVE LOW

This means that whatever is configured in the .dts is also showing up
in debugfs.
It doesn't mean that the correct GPIO or polarity is used -> that is
why I want to understand how to actually test this patch.
Technically I can write a patch that makes GPIOAO_13 (which is
connected to the status LED) show up as being used by
regulator-usb-pwr-en in debugfs.

[...]

quoted

quoted

 &usb1_phy {
        status = "okay";
+       phy-supply = <&usb_pwr_en>;

medium priority:
I have raised the following concern in one of my previous emails on this topic:

quoted

The mistake I made before is considering USB VBUS as PHY power supply.
I believe the USB PHY is actually powered by the AVDD18_USB_ADC and
USB33_VDDIOH signals. See the S905 datasheet [0], page 25
These are 1.8V and 3.3V signals while you are adding a 5V regulator.

you replied with:

quoted

OK, thanks.

so I don't understand what "OK, thanks" means.
If it means "Martin, you are wrong" then please provide a description
so I can also learn something!

Yes, I understood your inputs. But from the logs below is seen to
looking for phy-supply

This sentence is correct

This is the reason I went ahead with phy-supply as the core phy node
needs this property.

This sentence is not correct
From drivers/phy/phy-core.c:
    phy->pwr = regulator_get_optional(&phy->dev, "phy");

As you can see, the "phy-supply" regulator is marked as optional in
the PHY subsystem.
This matches with
Documentation/devicetree/bindings/phy/phy-bindings.txt where
"phy-supply" is marked as an optional property.

Please check below commit
e841ec956e53 ("ARM64: dts: meson-gxbb-odroidc2: fix usb1 power supply")

That commit is from 2017. You'll also find some commits where I am
also using the phy-supply property (I didn't know better back then).
However, in 2018 things changed when the dwc2 driver gained a
vbus-supply property in commit 531ef5ebea9639 ("usb: dwc2: add support
for host mode external vbus supply")
So for new .dts support phy-supply should not be used anymore for VBUS
because phy-supply (described as "Phandle to a regulator that provides
power to the PHY." in
Documentation/devicetree/bindings/phy/phy-bindings.txt) and
vbus-supply are two different things.


Best regards,
Martin

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