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Date:   Fri, 20 Jan 2023 20:48:55 +0530
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Subject: Re: [RFC v4 2/5] usb: dwc3: core: Refactor PHY logic to support
 Multiport Controller
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From:   Krishna Kurapati PSSNV <quic_kriskura@quicinc.com>
To:     Andrew Halaney <ahalaney@redhat.com>
CC:     Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        "Andy Gross" <agross@kernel.org>,
        Bjorn Andersson <andersson@kernel.org>,
        "Konrad Dybcio" <konrad.dybcio@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Felipe Balbi <balbi@kernel.org>, <linux-usb@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <linux-arm-msm@vger.kernel.org>,
        <devicetree@vger.kernel.org>, <quic_pkondeti@quicinc.com>,
        <quic_ppratap@quicinc.com>, <quic_wcheng@quicinc.com>,
        <quic_jackp@quicinc.com>, <quic_harshq@quicinc.com>,
        <quic_shazhuss@quicinc.com>
References: <20230115114146.12628-1-quic_kriskura@quicinc.com>
 <20230115114146.12628-3-quic_kriskura@quicinc.com>
 <20230119220942.ja5gbo3t3fl63gpy@halaney-x13s>
 <8f32c2e5-2743-1017-6a33-4849021c5287@quicinc.com>
 <20230120143717.ikbcb6x7wl4yy5d7@halaney-x13s>
 <84ad5269-dd48-32ef-1313-6241980834bc@quicinc.com>
In-Reply-To: <84ad5269-dd48-32ef-1313-6241980834bc@quicinc.com>
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On 1/20/2023 8:43 PM, Krishna Kurapati PSSNV wrote:
> 
> 
> On 1/20/2023 8:07 PM, Andrew Halaney wrote:
>> On Fri, Jan 20, 2023 at 07:25:57AM +0530, Krishna Kurapati PSSNV wrote:
>>>
>>>
>>> On 1/20/2023 3:39 AM, Andrew Halaney wrote:
>>>> On Sun, Jan 15, 2023 at 05:11:43PM +0530, Krishna Kurapati wrote:
>>>>> Currently the DWC3 driver supports only single port controller
>>>>> which requires at most one HS and one SS PHY.
>>>>>
>>>>> But the DWC3 USB controller can be connected to multiple ports and
>>>>> each port can have their own PHYs. Each port of the multiport
>>>>> controller can either be HS+SS capable or HS only capable
>>>>> Proper quantification of them is required to modify GUSB2PHYCFG
>>>>> and GUSB3PIPECTL registers appropriately.
>>>>>
>>>>> Add support for detecting, obtaining and configuring phy's supported
>>>>> by a multiport controller and limit the max number of ports
>>>>> supported to 4.
>>>>>
>>>>> Signed-off-by: Harsh Agarwal <quic_harshq@quicinc.com>
>>>>> Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com>
>>>>> ---
>>>>>    drivers/usb/dwc3/core.c | 304 
>>>>> +++++++++++++++++++++++++++++-----------
>>>>>    drivers/usb/dwc3/core.h |  15 +-
>>>>>    drivers/usb/dwc3/drd.c  |  14 +-
>>>>>    3 files changed, 244 insertions(+), 89 deletions(-)
>>>>>
>>>>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>>>>> index 476b63618511..7e0a9a598dfd 100644
>>>>> --- a/drivers/usb/dwc3/core.c
>>>>> +++ b/drivers/usb/dwc3/core.c
>>>>
>>>> <snip>
>>>>
>>>>> @@ -1575,6 +1690,21 @@ static void dwc3_get_properties(struct dwc3 
>>>>> *dwc)
>>>>>        dwc->dis_split_quirk = device_property_read_bool(dev,
>>>>>                    "snps,dis-split-quirk");
>>>>> +
>>>>> +    /*
>>>>> +     * If no mulitport properties are defined, default
>>>>> +     * the port count to '1'.
>>>>> +     */
>>>>> +    ret = device_property_read_u32(dev, "num-ports",
>>>>> +                &dwc->num_ports);
>>>>> +    if (ret)
>>>>> +        dwc->num_ports = 1;
>>>>> +
>>>>> +    ret = device_property_read_u32(dev, "num-ss-ports",
>>>>> +                &dwc->num_ss_ports);
>>>>> +    if (ret)
>>>>> +        dwc->num_ss_ports = 1;
>>>>
>>>> By using this DT property instead of using the number of each phy 
>>>> type you
>>>> find you can get into situations where you're writing 
>>>> DWC3_GUSB2PHYCFG, etc,
>>>> when there's no phy to go along with it.
>>>>
>>> Hi Andrew,
>>>
>>>   Thanks for the review. Yes, this decoupling is still there and its 
>>> fine I
>>> believe.
>>>
>>>> I ran into this when testing on sa8540p-ride, which only uses one of 
>>>> the
>>>> ports on the multiport controller. I didn't enable the other phys (not
>>>> sure if that was smart or not) and overrode phy-names/phys, but did not
>>>> override num-ports/num-ss-ports, which resulted in that. Nothing bad
>>>> happened on a quick test.. but I thought I'd highlight that as another
>>>> downside of decoupling this value from the number of phys you grab.
>>>>
>>> If we do not override phy-names or num-ports/num-ss-ports info in DT, 
>>> they
>>> are just defaulted to '1' and as per the current logic only port-1 
>>> registers
>>> must be configured. Isn't that the case happening ?
>>>
>>
>> In my dts I'm inheriting from the sc8280xp.dtsi usb_2 phandle you've 
>> created!
>> So unless I override them I get this from your sc8280xp.dtsi:
>>
>> +                       usb_2_dwc3: usb@a400000 {
>> +                               compatible = "snps,dwc3";
>> +                               reg = <0 0x0a400000 0 0xcd00>;
>> +                               interrupts = <GIC_SPI 133 
>> IRQ_TYPE_LEVEL_HIGH>;
>> +                               iommus = <&apps_smmu 0x800 0x0>;
>> +                               num-ports = <4>;
>> +                               num-ss-ports = <2>;
>> +                               phys = <&usb_2_hsphy0>, <&usb_2_qmpphy0>,
>> +                                       <&usb_2_hsphy1>, 
>> <&usb_2_qmpphy1>,
>> +                                       <&usb_2_hsphy2>,
>> +                                       <&usb_2_hsphy3>;
>> +                               phy-names = "usb2-phy_port0", 
>> "usb3-phy_port0",
>> +                                               "usb2-phy_port1", 
>> "usb3-phy_port1",
>> +                                               "usb2-phy_port2",
>> +                                               "usb2-phy_port3";
>> +                       };
>>
>> Since this board only uses one port of the multiport controller, I
>> redefined phys/phy-names to indicate that. I figured that was more
>> desireable than enabling unnecessary phys. Without overriding
>> num-ports/num-ss-ports all the for loops in this patch would act like
>> the values were 4 and 2 respectively, writing to DWC3_GUSB2PHYCFG
>> multiple times etc as well as look for the multiport phy-names and fail
>> to actually get any phys. Hope that makes sense!
>>
> Hi Andrew,
> 
>   My Bad. I missed the fact that it was based on sc8280xp.dtsi. In that 
> case it makes complete sense to override the num-ports and num-ss-ports 
> to "1" and the usb phy-names.
>>>> Here's a patch enabling sa8540p-ride, I'd love if you'd add it to the
>>>> series (probably needs clean up after review, and will definitely need
>>>> alteration after you update the dt-binding again). If not I'll continue
>>>> to test/review so please CC me!:
>>>>
>>>>
>>> Sure, I can add this patch (probably will add the other phy's too) 
>>> during
>>> the final submission.
>>
>> I don't have a great understanding of the mapping of the phys to
>> physical connections (as well as what registers like DWC3_GUSB2PHYCFG 
>> do),
>> so if it makes more sense to enable all the relevant SoC phys, write
>> those registers in the DWC3 IP, etc, and only use one of the actual
>> board outputs then feel free. I think this is a good example of "what if
>> a board designer only uses a single port of the multiport IP" imo.
>> Agreed. This could be a good example of multi port with only single port 

Typo in the previous mail. Correcting it here.

> working.
Agreed, The dt-patch you provided will be a good working example of 
getting just a single port working for a multiport controller.

Regards,
Krishna,

>>>
>>>>   From dcb27d07f079194ebd7efe1c9bec64da78beb290 Mon Sep 17 00:00:00 
>>>> 2001
>>>> From: Andrew Halaney <ahalaney@redhat.com>
>>>> Date: Thu, 19 Jan 2023 14:53:38 -0600
>>>> Subject: [PATCH] arm64: dts: qcom: sa8540p-ride: Enable usb_2
>>>> Content-type: text/plain
>>>>
>>>> There is now support for the multiport USB controller this uses
>>>> so enable it.
>>>>
>>>> The board only has a single port hooked up (despite it being wired 
>>>> up to
>>>> the multiport IP on the SoC). There's also a USB 2.0 mux hooked up,
>>>> which by default on boot is selected to mux properly. Grab the gpio
>>>> controlling that and ensure it stays in the right position so USB 2.0
>>>> continues to be routed from the external port to the SoC.
>>>>
>>>> Signed-off-by: Andrew Halaney <ahalaney@redhat.com>
>>>> ---
>>>>    arch/arm64/boot/dts/qcom/sa8540p-ride.dts | 24 
>>>> +++++++++++++++++++++++
>>>>    1 file changed, 24 insertions(+)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/qcom/sa8540p-ride.dts 
>>>> b/arch/arm64/boot/dts/qcom/sa8540p-ride.dts
>>>> index 97957f3baa64..56d4f43faa1e 100644
>>>> --- a/arch/arm64/boot/dts/qcom/sa8540p-ride.dts
>>>> +++ b/arch/arm64/boot/dts/qcom/sa8540p-ride.dts
>>>> @@ -246,6 +246,21 @@ &usb_0_qmpphy {
>>>>        status = "okay";
>>>>    };
>>>> +&usb_2 {
>>>> +    pinctrl-names = "default";
>>>> +    pinctrl-0 = <&usb2_en_state>;
>>>> +
>>>> +    status = "okay";
>>>> +};
>>>> +
>>>> +&usb_2_dwc3 {
>>>> +    dr_mode = "host";
>>>> +    num-ports = <1>;
>>>> +    num-ss-ports = <1>;
>>>
>>> More over, if this is a multiport controller and you are using only 
>>> port-1,
>>> it is as good as a single port controller I believe and the normal DT
>>> convention must work. Adding these properties as "1" is not required 
>>> as the
>>> driver logic defaults them to "1" if they are not found.
>>
>> See above comment about inheriting from sc8280xp.dtsi and needing to
>> override their values.
>>
>>>
>>> Just to add a point here (as I was not clear in DT Binding 
>>> description, My
>>> bad), the num-ports and num-ss-ports must indicate the HS/SS Phys 
>>> present on
>>> HW whether they are used in DT or not. Just to cover all cases which 
>>> user
>>> can use [1].
>>>
>>> []1:
>>> https://lore.kernel.org/all/4eb26a54-148b-942f-01c6-64e66541de8b@quicinc.com/ 
>>>
>>
>> Ok, if you're going with that approach of "must indicate the HS/SS Phys
>> present on HW whether they are used in the DT or not" (/me assumes DT
>> here means on the board and not an incorrect coding of the DT) then I
>> suppose I should not have overridden anything but phys/phy-names to
>> indicate that I'm only using the first port (and used the multiport
>> phy-names convention). It looks like in that link you also mention that
>> it is ok to write to DWC3_GUSB2PHYCFG and friends even if the phy isn't
>> defined, which was my concern and reasoning above for overriding
>> num-ports/num-ss-ports.
>>
>> Thanks,
>> Andrew
>>
> Actually, I was trying to mandate that rule to take care of cases where 
> the phy's for say port2 or port3 are missing for a quad port controller 
> in dtsi and we don't want to end up configuring wrong dwc3-phy regs.
> 
> For just the first port, the changes you have mentioned must be 
> sufficient. (Furthermore, thanks for the review and testing it on 
> sa8295-ride and confirming nothing breaks while the first port is enabled)
> 
> Regards,
> Krishna,
>>>
>>> Regards,
>>> Krishna,
>>>
>>>> +    phy-names = "usb2-phy", "usb3-phy";
>>>> +    phys = <&usb_2_hsphy0>, <&usb_2_qmpphy0>;
>>>> +};
>>>> +
>>>>    &usb_2_hsphy0 {
>>>>        vdda-pll-supply = <&vreg_l5a>;
>>>>        vdda18-supply = <&vreg_l7g>;
>>>> @@ -313,4 +328,13 @@ wake-pins {
>>>>                bias-pull-up;
>>>>            };
>>>>        };
>>>> +
>>>> +    usb2_en_state: usb2-en-state {
>>>> +        /* TS3USB221A USB2.0 mux select */
>>>> +        pins = "gpio24";
>>>> +        function = "gpio";
>>>> +        drive-strength = <2>;
>>>> +        bias-disable;
>>>> +        output-low;
>>>> +    };
>>>>    };
>>>
>>