linux-kernel - Re: [PATCH v5 4/7] usb: dwc3: core: Don't touch resets and clocks

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Message-ID: <bfba8edb-b1e9-4b9f-bf96-bcba35e0cd8f@linaro.org>
Date: Wed, 19 Mar 2025 16:52:50 +0100
From: neil.armstrong@...aro.org
To: Bjorn Andersson <bjorn.andersson@....qualcomm.com>,
 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>, Frank Li <Frank.li@....com>
Cc: linux-arm-msm@...r.kernel.org, linux-usb@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 4/7] usb: dwc3: core: Don't touch resets and clocks

On 18/03/2025 20:05, 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.
> 
> Reviewed-by: Frank Li <Frank.Li@....com>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@....qualcomm.com>
> ---
>   drivers/usb/dwc3/core.c | 20 +++++++++++---------
>   drivers/usb/dwc3/glue.h |  3 +++
>   2 files changed, 14 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index b428b6fc3d0a55811e2f75d33d79df4b0c67dcac..77a9848a0ac70fbe563988cecbe489130989aadc 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -2198,15 +2198,17 @@ 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)
> @@ -2321,7 +2323,7 @@ EXPORT_SYMBOL_GPL(dwc3_core_probe);
>   
>   static int dwc3_probe(struct platform_device *pdev)
>   {
> -	struct dwc3_probe_data probe_data;
> +	struct dwc3_probe_data probe_data = {};

This should go in the previous patch

Neil

>   	struct resource *res;
>   	struct dwc3 *dwc;
>   
> diff --git a/drivers/usb/dwc3/glue.h b/drivers/usb/dwc3/glue.h
> index e73cfc466012f07214291abe56454934ab014013..703d40c189565b1e28ae28afb8728b78f4cd2fca 100644
> --- a/drivers/usb/dwc3/glue.h
> +++ b/drivers/usb/dwc3/glue.h
> @@ -13,10 +13,13 @@
>    * dwc3_probe_data: Initialization parameters passed to dwc3_core_probe()
>    * @dwc: Reference to dwc3 context structure
>    * @res: resource for the DWC3 core mmio region
> + * @ignore_clocks_and_resets: clocks and resets defined for the device should
> + *		be ignored by the DWC3 core, as they are managed by the glue
>    */
>   struct dwc3_probe_data {
>   	struct dwc3 *dwc;
>   	struct resource *res;
> +	bool ignore_clocks_and_resets;
>   };
>   
>   int dwc3_core_probe(const struct dwc3_probe_data *data);
>