linux-kernel - Re: [PATCH v2 7/9] arm64: dts: amlogic: Used onboard usb hub reset on odroid c4

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Message-ID: <0dbefaec-e1de-fc3f-54f2-c5fe75a28c7c@linaro.org>
Date:   Wed, 18 Jan 2023 14:24:04 +0100
From:   neil.armstrong@...aro.org
To:     Anand Moon <linux.amoon@...il.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Kevin Hilman <khilman@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        linux-amlogic@...ts.infradead.org,
        Matthias Kaehlcke <mka@...omium.org>,
        Alexander Stein <alexander.stein@...tq-group.com>,
        Johan Hovold <johan@...nel.org>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 7/9] arm64: dts: amlogic: Used onboard usb hub reset on
 odroid c4

On 18/01/2023 12:55, Anand Moon wrote:
> Hi Neil,
> 
> Thanks for your review comments.
> 
> On Wed, 18 Jan 2023 at 13:59, Neil Armstrong <neil.armstrong@...aro.org> wrote:
>>
>> On 18/01/2023 05:44, Anand Moon wrote:
>>> On Odroid c4 previously use gpio-hog to reset the usb hub,
>>> switch to used on-board usb hub reset to enable the usb hub
>>> and enable power to hub.
>>>
>>> USB hub is combination of USB 2.0 and USB 3.0 root hub so
>>> use peer-hub node to link then.
>>>
>>> Signed-off-by: Anand Moon <linux.amoon@...il.com>
>>> ---
>>> v2: - fix the compatible string.
>>>       - Fix the hub node to use peer-hub to link the usb 2.0 and usb 3.0.
>>> ---
>>>    .../boot/dts/amlogic/meson-sm1-odroid-c4.dts  | 36 ++++++++++++-------
>>>    1 file changed, 23 insertions(+), 13 deletions(-)
>>>
>>> diff --git a/arch/arm64/boot/dts/amlogic/meson-sm1-odroid-c4.dts b/arch/arm64/boot/dts/amlogic/meson-sm1-odroid-c4.dts
>>> index 8c30ce63686e..d04768a66bfe 100644
>>> --- a/arch/arm64/boot/dts/amlogic/meson-sm1-odroid-c4.dts
>>> +++ b/arch/arm64/boot/dts/amlogic/meson-sm1-odroid-c4.dts
>>> @@ -26,20 +26,30 @@ led-blue {
>>>        sound {
>>>                model = "ODROID-C4";
>>>        };
>>> -};
>>>
>>> -&gpio {
>>> -     /*
>>> -      * WARNING: The USB Hub on the Odroid-C4 needs a reset signal
>>> -      * to be turned high in order to be detected by the USB Controller
>>> -      * This signal should be handled by a USB specific power sequence
>>> -      * in order to reset the Hub when USB bus is powered down.
>>> -      */
>>> -     hog-0 {
>>> -             gpio-hog;
>>> -             gpios = <GPIOH_4 GPIO_ACTIVE_HIGH>;
>>> -             output-high;
>>> -             line-name = "usb-hub-reset";
>>> +     /* USB hub supports both USB 2.0 and USB 3.0 root hub */
>>> +     usb-hub {
>>> +             dr_mode = "host";
>>
>> Is this really needed ?
>>
> I got carried forward from the other device tree binding,
> If not needed I will drop this.
> 
>>> +             #address-cells = <1>;
>>> +             #size-cells = <0>;
>>> +
>>> +             /* 2.0 hub on port 1 */
>>> +             hub_2_0: hub@1 {
>>> +                     compatible = "usb2109,2817";
>>> +                     reg = <1>;
>>> +                     peer-hub = <&hub_3_0>;
>>> +                     reset-gpios = <&gpio GPIOH_4 GPIO_ACTIVE_LOW>;
>>> +                     vdd-supply = <&vcc_5v>;
>>> +             };
>>> +
>>> +             /* 3.1 hub on port 4 */
>>> +             hub_3_0: hub@2 {
>>> +                     compatible = "usb2109,817";
>>> +                     reg = <2>;
>>> +                     peer-hub = <&hub_2_0>;
>>> +                     reset-gpios = <&gpio GPIOH_4 GPIO_ACTIVE_LOW>;
>>> +                     vdd-supply = <&vcc_5v>;
>>> +             };
>>
>> The final discussion in v1 was to drop this /usb-hub node and move the
>> hub_2_0 & hub_3_0 node under the dwc3 node.
>>
> 
> Yes, but It did not work back then, since these are two different events
> USB node will try to bring the PHY and dwc2 and dwc2 nodes up.
> USB hub supports the reset of the USB hub and links the power supply
> to the ports.
> This works on this board.

Forget the dwc2 node, the dwc2 since GXL is device mode only, so you need to put both
nodes in the dwc3 node which is host-only.

Neil

> 
>> Neil
>>
> Thanks
> 
> -Anand