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

From: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
To: Anand Moon <linux.amoon@gmail.com>
Cc: linux-phy@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org,
	Matt Corallo <oc2udbzfd@mattcorallo.com>,
	Rob Herring <robh+dt@kernel.org>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Kevin Hilman <khilman@baylibre.com>,
	Jerome Brunet <jbrunet@baylibre.com>,
	Kishon Vijay Abraham I <kishon@ti.com>,
	Vinod Koul <vkoul@kernel.org>,
	Emiliano Ingrassia <ingrassia@epigenesys.com>,
	Brian Kim <brian.kim@hardkernel.com>,
	devicetree@vger.kernel.org
Subject: Re: [PATCHv2 1/4] ARM: dts: meson8b: odroidc1: Add usb phy power node
Date: Sat, 17 Jul 2021 21:46:04 +0200	[thread overview]
Message-ID: <CAFBinCDeqauw_V-Vn9cat9HaCXj6HEMz6G+G+VbqCNtGEFGYzg@mail.gmail.com> (raw)
In-Reply-To: <20210716103651.1455-2-linux.amoon@gmail.com>

Hi Anand,

On Fri, Jul 16, 2021 at 12:37 PM Anand Moon <linux.amoon@gmail.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@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.

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