linux-kernel - Re: [PATCH] usb: dwc3: qcom: Provide stubs for dwc3_qcom_read_usb2

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Message-ID: <CAA8EJpq=+y7ZOrdAoA-RsLLPgLn5hi+TaTvqetrwz93E+ONjKA@mail.gmail.com>
Date:   Sun, 31 Jul 2022 09:33:12 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Krishna Kurapati <quic_kriskura@...cinc.com>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Randy Dunlap <rdunlap@...radead.org>,
        linux-arm-msm@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: dwc3: qcom: Provide stubs for dwc3_qcom_read_usb2_speed
 function

On Sun, 31 Jul 2022 at 06:19, Krishna Kurapati
<quic_kriskura@...cinc.com> wrote:
>
> This patch intends to fix a build issue that is occurring due to

Please refrain from the "This patch" phrase. See the
Documentation/process/submitting-patches.rst for the suggestions for
the commit message.

> dwc3_qcom_read_usb2_speed function which uses usb_hub_find_child API
> in its effors to get the speed of devices (HS/FS/LS) connected.
>
> usb_hub_find_child API is a part of usb core compiled into the kernel
> when CONFIG_USB=y. In some builds (make randconfig for i386)
> CONFIG_USB is not set and the usb core is not compiled into the
> kernel causing linking errors.
>
> Provide stubs for dwc3_qcom_read_usb2_speed function to use
> usb_hub_find_child API only if CONFIG_USB is set. Else return
> USB_SPEED_UNKNOWN.

The commit message describes the issue in terms of CONFIG_USB being
compiled into the kernel or not. It is not clear if the issue
manifests with CONFIG_USB=m (which is also 'not compiled into the
kernel').
If I understand correctly, the cause for linking errors is not in the
CONFIG_USB being not compiled into the kernel, but in CONFIG_USB being
not enabled at all (which is possible since USB_DWC3 depends on USB ||
USB_GADGET).
If my understanding is correct, I'd suggest changing the commit
message to describe the cause rather than just the issue you observed
on randconfig failure.

>
> Fixes: 6895ea55c385 (usb: dwc3: qcom: Configure wakeup interrupts during suspend)
> Reported-by: Randy Dunlap <rdunlap@...radead.org>
> Signed-off-by: Krishna Kurapati <quic_kriskura@...cinc.com>
> ---
>  drivers/usb/dwc3/dwc3-qcom.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
> index c5e482f..bd8dc5a 100644
> --- a/drivers/usb/dwc3/dwc3-qcom.c
> +++ b/drivers/usb/dwc3/dwc3-qcom.c
> @@ -299,6 +299,7 @@ static void dwc3_qcom_interconnect_exit(struct dwc3_qcom *qcom)
>         icc_put(qcom->icc_path_apps);
>  }
>
> +#ifdef CONFIG_USB
>  static enum usb_device_speed dwc3_qcom_read_usb2_speed(struct dwc3_qcom *qcom)
>  {
>         struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3);
> @@ -318,6 +319,12 @@ static enum usb_device_speed dwc3_qcom_read_usb2_speed(struct dwc3_qcom *qcom)
>
>         return udev->speed;
>  }
> +#else
> +static enum usb_device_speed dwc3_qcom_read_usb2_speed(struct dwc3_qcom *qcom)
> +{
> +       return USB_SPEED_UNKNOWN;
> +}
> +#endif
>
>  static void dwc3_qcom_enable_wakeup_irq(int irq, unsigned int polarity)
>  {
> --
> 2.7.4
>


-- 
With best wishes
Dmitry