linux-kernel - Re: [PATCH v6 2/4] usb: dwc3: qcom: Add interconnect support in dwc3 driver

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Message-ID: <20200329171756.GA199755@google.com>
Date:   Sun, 29 Mar 2020 10:17:56 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Sandeep Maheswaram <sanm@...eaurora.org>,
        Felipe Balbi <balbi@...nel.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Felipe Balbi <balbi@...nel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Doug Anderson <dianders@...omium.org>,
        linux-arm-msm@...r.kernel.org, linux-usb@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Manu Gautam <mgautam@...eaurora.org>,
        Chandana Kishori Chiluveru <cchiluve@...eaurora.org>
Subject: Re: [PATCH v6 2/4] usb: dwc3: qcom: Add interconnect support in dwc3
 driver

Hi,

On Fri, Mar 27, 2020 at 03:13:21PM +0530, Sandeep Maheswaram wrote:
> Add interconnect support in dwc3-qcom driver to vote for bus
> bandwidth.
> 
> This requires for two different paths - from USB master to
> DDR slave. The other is from APPS master to USB slave.
> 
> Signed-off-by: Sandeep Maheswaram <sanm@...eaurora.org>
> Signed-off-by: Chandana Kishori Chiluveru <cchiluve@...eaurora.org>
> Reviewed-by: Matthias Kaehlcke <mka@...omium.org>
> ---
>  drivers/usb/dwc3/dwc3-qcom.c | 128 ++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 126 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
> index 1dfd024..7e85fe6 100644
> --- a/drivers/usb/dwc3/dwc3-qcom.c
> +++ b/drivers/usb/dwc3/dwc3-qcom.c
>
> ...
>
> +/* To disable an interconnect, we just set its bandwidth to 0 */
> +static int dwc3_qcom_interconnect_disable(struct dwc3_qcom *qcom)
> +{
> +	int ret;
> +
> +	ret = icc_set_bw(qcom->usb_ddr_icc_path, 0, 0);
> +	if (ret)
> +		return ret;
> +
> +	ret = icc_set_bw(qcom->apps_usb_icc_path, 0, 0);
> +	if (ret)
> +		goto err_reenable_memory_path;
> +
> +	return 0;
> +
> +	/* Re-enable things in the event of an error */
> +err_reenable_memory_path:
> +	ret = dwc3_qcom_interconnect_enable(qcom);

This overwrites the error that led to the execution of this code path.
The function should return original error, not the result of the
_interconnect_enable() call.

I saw Felipe queued the patch for v5.8. I think the main options to fix this
are:

- a v6 of this patch to replace v5 in Felipe's tree (which IIUC will be rebased
  anyway once there is a v5.7-rc)
- send the fix as a separate patch
- Felipe amends the patch in his tree

Felipe, what would work best for you?

Thanks

Matthias