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

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Date:   Thu, 5 Aug 2021 23:48:20 +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 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.

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

Thanks
-Anand