Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20210817041548.1276-1-linux.amoon@gmail.com> <20210817041548.1276-2-linux.amoon@gmail.com>
 <c7f6213b-5ddc-881c-1aea-9cc7b03e6a4f@baylibre.com> <CAFBinCBeNMET2tvH0h6HF3dR+xBb59hifQyaoXigUs3UGkS+KQ@mail.gmail.com>
 <2b07b3de-cee5-c570-8fde-6a4c684122d6@baylibre.com> <CANAwSgRNp8UtU+Yy4smwZ5POTWTU+xN1mrf_cH7Pu9yX5HU=VA@mail.gmail.com>
 <CAFBinCDmNt+aXRE4xFZdegOUs8BqJiTPF3+DQ-buvWWXrQLkdw@mail.gmail.com>
In-Reply-To: <CAFBinCDmNt+aXRE4xFZdegOUs8BqJiTPF3+DQ-buvWWXrQLkdw@mail.gmail.com>
From:   Anand Moon <linux.amoon@gmail.com>
Date:   Sat, 25 Sep 2021 23:11:58 +0530
Message-ID: <CANAwSgTcTCNWD3QTt4-c8BeAbFxDewbZewaSouggPuK9cpSXog@mail.gmail.com>
Subject: Re: [PATCHv3 1/6] ARM: dts: meson8b: odroidc1: Add usb phy power node
To:     Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc:     Neil Armstrong <narmstrong@baylibre.com>,
        linux-phy@lists.infradead.org,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        linux-amlogic@lists.infradead.org,
        Linux Kernel <linux-kernel@vger.kernel.org>,
        devicetree <devicetree@vger.kernel.org>,
        Matt Corallo <oc2udbzfd@mattcorallo.com>,
        Rob Herring <robh+dt@kernel.org>,
        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>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Hi Martin,

On Tue, 21 Sept 2021 at 00:56, Martin Blumenstingl
<martin.blumenstingl@googlemail.com> wrote:
>
> Hi Anand,
>
> On Tue, Aug 31, 2021 at 10:48 PM Anand Moon <linux.amoon@gmail.com> wrote:
> [...]
> > After enabling CONFIG_REGULATOR_DEBUG, with this patch applied
> > I still not getting the USB regulator to enable.
> > Do you see different output at your end?
> I don't have much time for testing and debugging currently but I'll
> put it on my TODO-list
> Until either of us has found the issue I suggest not merging this patch.
>
Ok no problem.

Basically, I have just roughly gone through the architecture of
Amlogic's OTG framework.
Below is the global configuration registers for DWC2 OTG framer work

[0] https://github.com/hardkernel/linux/blob/odroidc-3.10.y/drivers/amlogic/usb/dwc_otg/310/dwc_otg_regs.h#L66-L151

Within some configurations, it helps tune the power for vbus and interrupt
For example
[1] https://github.com/hardkernel/linux/blob/odroidc-3.10.y/drivers/amlogic/usb/dwc_otg/310/dwc_otg_attr.c#L666-L717

Amlogic basically used the mode parameter to external tune the DWC2 driver
it could help more fine-tuning the driver.

[2] https://github.com/hardkernel/linux/blob/odroidc-3.10.y/drivers/amlogic/usb/dwc_otg/310/dwc_otg_driver.c#L1461-L1703

I feel we need to identify many more PHY tuning parameters to make the
USB work correctly.


Thanks
-Anand

>
> Best regards,
> Martin