linux-kernel - Re: [PATCH v4 3/7] usb: dwc3: core: Don't touch resets and clocks

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Message-ID: <Z8C7cRKMmvUlV6vQ@lizhi-Precision-Tower-5810>
Date: Thu, 27 Feb 2025 14:22:25 -0500
From: Frank Li <Frank.li@....com>
To: Bjorn Andersson <bjorn.andersson@....qualcomm.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Felipe Balbi <balbi@...nel.org>,
	Wesley Cheng <quic_wcheng@...cinc.com>,
	Saravana Kannan <saravanak@...gle.com>,
	Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konradybcio@...nel.org>,
	linux-arm-msm@...r.kernel.org, linux-usb@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/7] usb: dwc3: core: Don't touch resets and clocks

On Wed, Feb 26, 2025 at 04:17:50PM -0800, Bjorn Andersson wrote:
> When the core is integrated with glue, it's reasonable to assume that
> the glue driver will have to touch the IP before/after the core takes
> the hardware out and into reset. As such the glue must own these
> resources and be allowed to turn them on/off outside the core's
> handling.
>
> Allow the platform or glue layer to indicate if the core logic for
> clocks and resets should be skipped to deal with this.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@....qualcomm.com>
> ---
>  drivers/usb/dwc3/core.c | 19 +++++++++++--------
>  drivers/usb/dwc3/glue.h |  1 +
>  2 files changed, 12 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index d9f0a6782d36..aecdde8dc999 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -2187,15 +2187,17 @@ int dwc3_core_probe(const struct dwc3_probe_data *data)
>  	if (IS_ERR(dwc->usb_psy))
>  		return dev_err_probe(dev, PTR_ERR(dwc->usb_psy), "couldn't get usb power supply\n");
>
> -	dwc->reset = devm_reset_control_array_get_optional_shared(dev);
> -	if (IS_ERR(dwc->reset)) {
> -		ret = PTR_ERR(dwc->reset);
> -		goto err_put_psy;
> -	}
> +	if (!data->ignore_clocks_and_resets) {
> +		dwc->reset = devm_reset_control_array_get_optional_shared(dev);
> +		if (IS_ERR(dwc->reset)) {
> +			ret = PTR_ERR(dwc->reset);
> +			goto err_put_psy;
> +		}
>
> -	ret = dwc3_get_clocks(dwc);
> -	if (ret)
> -		goto err_put_psy;
> +		ret = dwc3_get_clocks(dwc);
> +		if (ret)
> +			goto err_put_psy;
> +	}
>
>  	ret = reset_control_deassert(dwc->reset);
>  	if (ret)
> @@ -2328,6 +2330,7 @@ static int dwc3_probe(struct platform_device *pdev)
>
>  	probe_data.dwc = dwc;
>  	probe_data.res = res;
> +	probe_data.ignore_clocks_and_resets = false;
>
>  	return dwc3_core_probe(&probe_data);
>  }
> diff --git a/drivers/usb/dwc3/glue.h b/drivers/usb/dwc3/glue.h
> index e73cfc466012..1ddb451bdbd0 100644
> --- a/drivers/usb/dwc3/glue.h
> +++ b/drivers/usb/dwc3/glue.h
> @@ -17,6 +17,7 @@
>  struct dwc3_probe_data {
>  	struct dwc3 *dwc;
>  	struct resource *res;
> +	bool ignore_clocks_and_resets;

Nit: suggest add kernel doc comments for each fields

Reviewed-by: Frank Li <Frank.Li@....com>

>  };
>
>  int dwc3_core_probe(const struct dwc3_probe_data *data);
>
> --
> 2.45.2
>