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

[Anand Moon <linux.amoon@gmail.com>]

Hi Martin,

Thanks for your valuable feedback,

On Sun, 18 Jul 2021 at 17:07, Martin Blumenstingl
<martin.blumenstingl@googlemail.com> wrote:
>
> Hi Anand,
>
> On Sun, Jul 18, 2021 at 5:38 AM Anand Moon <linux.amoon@gmail.com> wrote:
> [...]
> > > > 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.

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

Yep, you are correct, If I used GPIOAO_13 wrong pin, it will not
enable the USB power. See below.
[alarm@archl-c1e ~]$ sudo cat /sys/kernel/debug/gpio | grep usb
 gpio-1953 (USB_HUB_RST_N       |usb-hub-reset       ) out hi

So correct way with  gpios = <&gpio_ao GPIOAO_5 GPIO_ACTIVE_LOW>;

[alarm@archl-c1e linux-amlogic-5.y-devel]$ 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

The reason for USB ports has power without this patch is applied.
Please check schematics S805 USB2 SDB
USB_VDD33 is powered with VDDIO_AO3V3 regulator directly along with SD CARD.

>
> [...]
> > > >  &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!
> >
> > 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")
OK.
> 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.
>

It just came to my notice your email on this issue sees below.
[0] https://patchwork.kernel.org/project/linux-usb/patch/20190306212431.5779-1-martin.blumenstingl@googlemail.com/
[1] https://patchwork.kernel.org/patch/10868515/
[2] https://git.openwrt.org/?p=openwrt/openwrt.git;a=commitdiff;h=d8b475212bbf9e5f80c1c923a9701dca5ceb23e2

From the openwrt commit  d8b475212bbf9e5f80c1c923a9701dca5ceb23e2
and binding yaml  [3]
https://elixir.bootlin.com/linux/latest/source/Documentation/devicetree/bindings/usb/dwc2.yaml#L87

USB DWC2 power is linked to vbus-supply, so it should be moved to usb node.
Now I am getting your point correctly.

[    1.260460] dwc2 c90c0000.usb: Looking up vusb_d-supply property in
node /soc/usb@c90c0000 failed
[    1.260490] dwc2 c90c0000.usb: supply vusb_d not found, using dummy regulator
[    1.260606] dwc2 c90c0000.usb: Looking up vusb_a-supply from device tree
[    1.260620] dwc2 c90c0000.usb: Looking up vusb_a-supply property in
node /soc/usb@c90c0000 failed
[    1.260641] dwc2 c90c0000.usb: supply vusb_a not found, using dummy regulator
[    1.260717] dwc2 c90c0000.usb: registering common handler for irq35
[    1.260772] dwc2 c90c0000.usb: Looking up vbus-supply from device tree
[    1.260784] dwc2 c90c0000.usb: Looking up vbus-supply property in
node /soc/usb@c90c0000 failed

Thanks for the input, I will update the vbus-supply in the next
version to USB nodes.

>
> Best regards,
> Martin

Thanks
-Anand