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

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Date:   Sat, 14 Aug 2021 01:05:40 +0530
From:   Anand Moon <linux.amoon@...il.com>
To:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     linux-phy@...ts.infradead.org,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-amlogic@...ts.infradead.org,
        Linux Kernel <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>,
        devicetree <devicetree@...r.kernel.org>
Subject: Re: [PATCHv2 1/4] ARM: dts: meson8b: odroidc1: Add usb phy power node

Hi Martin,

On Thu, 5 Aug 2021 at 23:48, Anand Moon <linux.amoon@...il.com> wrote:
>
> Hi Martin,
>
> On Thu, 5 Aug 2021 at 03:28, Martin Blumenstingl
> <martin.blumenstingl@...glemail.com> wrote:
> >
> > On Sun, Jul 18, 2021 at 9:09 PM Martin Blumenstingl
> > <martin.blumenstingl@...glemail.com> wrote:
> > >
> > > Hi Anand,
> > >
> > > On Sun, Jul 18, 2021 at 4:01 PM Martin Blumenstingl
> > > <martin.blumenstingl@...glemail.com> wrote:
> > > [...]
> > > > > From the schematics [1]
> > > > > https://dn.odroid.com/S805/Schematics/odroid-c1+_rev0.4_20160226.pdf
> > > > >
> > > > > You could find references to PWREN  <--- GPIOAO.BIT5
> > > > > The second reference is USB HOST Power Switch
> > > > > The third reference is USB HOST POWER.
> > > > >
> > > > > Hope I am clean in my thought process now.
> > > > Can you please point out the page numbers for me?
> > > >
> > > > What I am seeing on page 1 is:
> > > > GPIOAO_5 (called GPIOAO.BIT5) is connected as an INPUT to the USB_OTG
> > > > PWREN signal (that's the green box with the label "USB_OTG.SchDoc"
> > > > above it).
> > > I unfortunately missed your question on IRC on this topic:
> > > <armoon> xdarklight: just want to understand the confusion on PWREN,
> > > either is INPUT / OTPUT to usb hub am I correct
> > > My understanding of the INPUT/OUTPUT direction in the Odroid-C1
> > > schematics (which you linked) above is that the arrow direction shows
> > > whether it's an input or output.
> > > For example (all on page one):
> > > - HDMI_HPD is an input to the Meson8b SoC, arrow direction is: HDMI => S805
> > > - IR_IN is an input to the Meson8b SoC, arrow direction is: S805 <=
> > > GPIOAO.BIT7 IR_IN
> > > - PWM is an output, arrow direction is: S805 => PWM.C VCCK_PWM
> > > - 3.3V/1.8V switch for the SD card is an output, arrow direction is:
> > > S805 => GPIOAO.BIT3 TF_3V3N_1V8_EN
> > >
> > > That tells me: the arrow direction shows which connections are inputs
> > > or outputs.
> > > Some pins can be input and output at the same time (HDMI_CEC). But
> > > let's keep it simple for now any only look at inputs/output.
> > >
> > > Based on this information I am looking at the arrow direction for
> > > USB_OTG: GPIOAO.BIT5 PWREN <= S805
> > > So this confirms that GPIOAO_5 is an output to the SoC.
> > > Please note though that this part is not linked with any USB host
> > > connector, it's only linked to the USB OTG path.
> > >
> > > For the next part the S805 SoC is not involved:
> > > USB1 USB_HOST_PWR_SW PWREN <= PWREN USB_HUB_GL852G
> > > USB2 USB_HOST_PWR_SW PWREN <= PWREN USB_HUB_GL852G
> > > This tells me that the PWREN signal for the two USB_HOST_PWR_SW (USB
> > > host power switches / current limiters) is driven by the GL852G USB
> > > hub.
> > Hardkernel team responded on the Odroid forums to the request from Anand:
> > "Power-Enable signal to the USB load switch ICs is connected to the
> > USB hub controller.
> > It is not connected the CPU GPIO."
> >
> > The regulator from Anand's patch is therefore connected to the micro USB port.
> > This means that the patch needs updating in case Anand wants to have
> > it included.
> >
>
> Yes, I will send a corrected version of the patches soon.

I have a small query regarding GPIO polarity

As per the datasheet of *MP62551DGT-LF-Z*
[0] https://www.mouser.in/datasheet/2/277/MP62550-1384050.pdf

USB power enables EN signal need to be Active High.

PIN Fucntion > Enable input. Active Low: (MP62550), Active High: (MP62551).

So the correct option in dts
+               /*
+                * signal name from schematics: PWREN - GPIOAO.BIT5
+                */
+               gpios = <&gpio_ao GPIOAO_5 GPIO_ACTIVE_HIGH>;
+               enable-active-high;

which gives me the below output.

$  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 hi

Please clear this small query so that I can send the update patch.

Thanks
-Anand

>
> >
> > Best regards,
> > Martin
> >
> >
> > [0] https://forum.odroid.com/viewtopic.php?p=332217#p332217
>
> Thanks
> -Anand