linux-kernel - Re: [RFCv1 4/8] phy: amlogic: meson8b-usb2: Use phy set

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Message-ID: <CANAwSgTd1zq_gHbVZesLY=e3DRRGgn_o5omuDo9Lub4FavOtbQ@mail.gmail.com>
Date:   Mon, 21 Jun 2021 12:50:37 +0530
From:   Anand Moon <linux.amoon@...il.com>
To:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     Kishon Vijay Abraham I <kishon@...com>,
        Vinod Koul <vkoul@...nel.org>,
        Neil Armstrong <narmstrong@...libre.com>,
        Kevin Hilman <khilman@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        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>
Subject: Re: [RFCv1 4/8] phy: amlogic: meson8b-usb2: Use phy set_mode callback function

Hi Martin,

On Sat, 19 Jun 2021 at 01:31, Martin Blumenstingl
<martin.blumenstingl@...glemail.com> wrote:
>
> Hi Anand,
>
> On Fri, Jun 18, 2021 at 3:19 PM Anand Moon <linux.amoon@...il.com> wrote:
> [...]
> > > I suggest dropping this patch until we know for sure if and which
> > > registers need to be updated based on the DR mode.
> >
> > Yes, I have observed this, Can you give these small changes a try?
> > With the below changes, I got the  PHY_MODE_USB_DEVICE support working.
> first of all: sorry that I have not linked my source of information previously:
> - Meson8b: [0]
> - Meson8 and Meson8m2: [1]
>
> Unfortunately I don't have any datasheet or "better documentation" of
> how the registers should be programmed.
> This is why I am a bit defensive when I am asked to change something
> there - as I simply have no way of knowing if the changes are good or
> not. I can only tell whether they're "identical" or "different" from
> what the vendor kernel does.
>
> [...]
> > +       case PHY_MODE_USB_DEVICE:
> > +       case PHY_MODE_USB_OTG:
> > +               regmap_update_bits(priv->regmap, REG_ADP_BC,
> > +                                  REG_ADP_BC_DCD_ENABLE,
> > +                                  REG_ADP_BC_DCD_ENABLE);
> > +
> > +               udelay(ACA_ENABLE_COMPLETE_TIME);
> > +
> > +               regmap_read(priv->regmap, REG_ADP_BC, &reg);
> > +               if (reg & REG_ADP_BC_ACA_PIN_FLOAT) {
> > +                       dev_warn(&phy->dev, "USB ID detect failed!\n");
> > +                       return -EINVAL;
> > +               }
> > +               regmap_update_bits(priv->regmap, REG_ADP_BC,
> > +                                  REG_ADP_BC_ID_PULLUP, REG_ADP_BC_ID_PULLUP);
> > +               break;
> According to the vendor kernel this should only be applied to
> "host-only" USB_PORT_IDX_B (which is usb1 in the mainline .dtsi).
> Based on that I think it's not correct to apply this for DEVICE and OTG modes.
>
> The vendor kernel does not configure REG_ADP_BC_ID_PULLUP anywhere.
> Also DCD_ENABLE is only ever set to 0 (while you are enabling it now), see [2].
>
> As mentioned before: all I can say about this patch is that it
> programs the registers differently than the vendor kernel does.
> From your description I am not sure if you are now getting different
> behavior on Odroid-C1 with this patch (compared to what we had
> before).
>

In order to enable USB phy we probably need to do a little bit
differently than the vendor kernel.
Yes I have observed many configuration parameters are missing.

OTG port on Odroid C1+ and Odroid C2 server two purposes
1 > It could act as USB host port.
2 > It could be used as USB power on the devices, just like Raspberry pi.
      What I meant is we need some driver code to protect the power to SbC.

So depending on the mode, it gets configured host mode or PCD mode,
I am not completely sure right now.
So I saw your work on extcon, that's the reason I would like to void
any changes PHY right now.

I observe some failures like below.
[    6.013859] dwc2 c9000000.usb: DWC OTG HCD URB Dequeue
[    6.013897] dwc2 c9000000.usb: Called usb_hcd_giveback_urb()
[    6.013902] dwc2 c9000000.usb:   urb->status = -115

Still investigating this issue,

>
> Best regards,
> Martin
>
Yes, I will go through the features for debugging in the future.
>
> [0] https://github.com/endlessm/linux-meson/blob/03393bb8e8478626e03ee93b0a2a225d6de242b5/arch/arm/mach-meson8b/usbclock.c#L120
> [1] https://github.com/endlessm/linux-meson/blob/03393bb8e8478626e03ee93b0a2a225d6de242b5/arch/arm/mach-meson8/usbclock.c#L120
> [2] https://github.com/endlessm/linux-meson/blob/d6e13c220931110fe676ede6da69fc61a7cb04b6/drivers/amlogic/usb/dwc_otg/310/dwc_otg_pcd.c#L71

Thanks
-Anand