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

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Message-ID: <20250321215254.hmchw64vafqu3joq@synopsys.com>
Date: Fri, 21 Mar 2025 21:52:56 +0000
From: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To: "neil.armstrong@...aro.org" <neil.armstrong@...aro.org>
CC: 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>,
        "linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 4/7] usb: dwc3: core: Don't touch resets and clocks

On Wed, Mar 19, 2025, neil.armstrong@...aro.org wrote:
> 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
> 

This should be fine to be here since it may not be necessary for the
previous patch.

BR,
Thinh


> >   	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);
> > 
>