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

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Date:   Sat, 17 Jul 2021 21:46:04 +0200
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     Anand Moon <linux.amoon@...il.com>
Cc:     linux-phy@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Matt Corallo <oc2udbzfd@...tcorallo.com>,
        Rob Herring <robh+dt@...nel.org>,
        Neil Armstrong <narmstrong@...libre.com>,
        Kevin Hilman <khilman@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Kishon Vijay Abraham I <kishon@...com>,
        Vinod Koul <vkoul@...nel.org>,
        Emiliano Ingrassia <ingrassia@...genesys.com>,
        Brian Kim <brian.kim@...dkernel.com>,
        devicetree@...r.kernel.org
Subject: Re: [PATCHv2 1/4] ARM: dts: meson8b: odroidc1: Add usb phy power node

Hi Anand,

On Fri, Jul 16, 2021 at 12:37 PM Anand Moon <linux.amoon@...il.com> wrote:
>
> Add missing usb phy power node for phy mode fix below warning.
> P5V0 regulator suppy input voltage range to USB host controller.
low prio - typo: suppy -> supply

> As descriped in the C1+ schematics, GPIO GPIOAO_5 is used to
low prio - typo: descriped -> described

> 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@...00000/phy@...0 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.

[...]
> +               /*
> +                * 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

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
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

[...]
>  &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:
> 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:
> 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!


Best regards,
Martin