linux-kernel - Re: [PATCH v14 0/9] Add multiport support for DWC3 controllers

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Message-ID: <f86cb527-3f91-4961-bbd5-4dc0e9a42df7@quicinc.com>
Date: Tue, 6 Feb 2024 13:45:35 +0530
From: Krishna Kurapati PSSNV <quic_kriskura@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC: Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring
	<robh+dt@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Wesley Cheng
	<quic_wcheng@...cinc.com>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        "Greg
 Kroah-Hartman" <gregkh@...uxfoundation.org>,
        Conor Dooley
	<conor+dt@...nel.org>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Felipe Balbi
	<balbi@...nel.org>, <devicetree@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <quic_ppratap@...cinc.com>,
        <quic_jackp@...cinc.com>
Subject: Re: [PATCH v14 0/9] Add multiport support for DWC3 controllers



On 2/6/2024 1:30 PM, Dmitry Baryshkov wrote:
> Hi Krishna,
> 
> On Tue, 6 Feb 2024 at 07:18, Krishna Kurapati <quic_kriskura@...cinc.com> wrote:
>>
>> Currently the DWC3 driver supports only single port controller which
>> requires at most two PHYs ie HS and SS PHYs. There are SoCs that has
>> DWC3 controller with multiple ports that can operate in host mode.
>> Some of the port supports both SS+HS and other port supports only HS
>> mode.
>>
>> This change primarily refactors the Phy logic in core driver to allow
>> multiport support with Generic Phy's.
>>
>> Changes have been tested on  QCOM SoC SA8295P which has 4 ports (2
>> are HS+SS capable and 2 are HS only capable).
> 
> Thank you for your patches! Have you tested how this patchset
> interacts with the USB role-switching?
> 
> I'm asking because it might be easier to define DT nodes for each of
> USB ports, which can carry the PHY properties (and also other DT
> properties if that's required, e.g. the ports / endpoints and
> usb-role-switch) rather than pushing all USB PHY links to the root DT
> node.
> 

Hi Dmitry,

  Role switching doesn't work for Multiport controller as it is host 
only capable. I don't think it will cause any issues for OTG capable 
controllers because they only have one HS and SS phy present. So there 
is no possibility or requirement for having endpoints per port in this case.

Regards,
Krishna,