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From:   Doug Anderson <dianders@chromium.org>
Date:   Wed, 11 Dec 2019 11:43:28 -0800
Message-ID: <CAD=FV=Uy6ryrbpzFg1sesJkWrgh05tLgvtozx0afJPF_u4-ESA@mail.gmail.com>
Subject: Re: [PATCH v2 1/3] usb: dwc3: Add support for SC7180 SOC
To:     Sandeep Maheswaram <sanm@codeaurora.org>
Cc:     Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Felipe Balbi <balbi@kernel.org>,
        Stephen Boyd <swboyd@chromium.org>,
        linux-arm-msm <linux-arm-msm@vger.kernel.org>,
        linux-usb@vger.kernel.org,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>
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Sender: linux-kernel-owner@vger.kernel.org
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Hi,

On Thu, Nov 28, 2019 at 3:35 AM Sandeep Maheswaram <sanm@codeaurora.org> wrote:
>
> Add compatible for SC7180 SOC in USB DWC3 driver
>
> Signed-off-by: Sandeep Maheswaram <sanm@codeaurora.org>
> ---
>  drivers/usb/dwc3/dwc3-qcom.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
> index 261af9e..1df2372 100644
> --- a/drivers/usb/dwc3/dwc3-qcom.c
> +++ b/drivers/usb/dwc3/dwc3-qcom.c
> @@ -1,5 +1,5 @@
>  // SPDX-License-Identifier: GPL-2.0
> -/* Copyright (c) 2018, The Linux Foundation. All rights reserved.
> +/* Copyright (c) 2018-2019, The Linux Foundation. All rights reserved.
>   *
>   * Inspired by dwc3-of-simple.c
>   */
> @@ -753,6 +753,7 @@ static const struct of_device_id dwc3_qcom_of_match[] = {
>         { .compatible = "qcom,dwc3" },
>         { .compatible = "qcom,msm8996-dwc3" },
>         { .compatible = "qcom,msm8998-dwc3" },
> +       { .compatible = "qcom,sc7180-dwc3" },
>         { .compatible = "qcom,sdm845-dwc3" },

It is, of course, up to Felipe.  ...but in my opinion this is the
wrong change and instead we should be deleting the SoC-specific
strings (msm8996, msm8998, sdm845) from this file because they don't
buy us anything.  To explain how it works:

1. Device tree should have both the "SoC-specific" and generic
"qcom,dwc3" strings.  Only the "qcom,dwc3" will actually be used but
the SoC-specific string is there so if we find a case later where we
need to handle a SoC-specific quirk then it'll already be there.

2. Bindings should have both the "SoC-specific" and generic
"qcom,dwc3" strings.  The binding is describing what's in the device
tree.

3. Until we have a SoC-specific quirk to handle, we _don't_ need to
add the SoC-specific string to the driver itself.


-Doug