Re: [PATCH] usb: dwc3: qcom: Add shutdown callback for dwc3

[sanm]

On 2021-01-13 14:10, Felipe Balbi wrote:
> Hi,
>
> Sandeep Maheswaram <sanm@xxxxxxxxxxxxxx> writes:
> > This patch adds a shutdown callback to USB DWC QCOM driver to ensure 
> > that
> > it is properly shutdown in reboot/shutdown path. This is required
> > where SMMU address translation is enabled like on SC7180
> > SoC and few others. If the hardware is still accessing memory after
> > SMMU translation is disabled as part of SMMU shutdown callback in
> > system reboot or shutdown path, then IOVAs(I/O virtual address)
> > which it was using will go on the bus as the physical addresses which
> > might result in unknown crashes (NoC/interconnect errors).
> >
> > Signed-off-by: Sandeep Maheswaram <sanm@xxxxxxxxxxxxxx>
>
> sounds like this is fixing a bug. Do you have a Fixes tag for it? 
> Should
> this go to stable?
Didn't encounter any bug till now but made this change to prevent issue.

> > diff --git a/drivers/usb/dwc3/dwc3-qcom.c 
> > b/drivers/usb/dwc3/dwc3-qcom.c
> > index c703d55..a930e06 100644
> > --- a/drivers/usb/dwc3/dwc3-qcom.c
> > +++ b/drivers/usb/dwc3/dwc3-qcom.c
> > @@ -790,13 +790,11 @@ static int dwc3_qcom_probe(struct 
> > platform_device *pdev)
> >  	return ret;
> >  }
> >
> > -static int dwc3_qcom_remove(struct platform_device *pdev)
> > +static void __dwc3_qcom_teardown(struct dwc3_qcom *qcom)
> >  {
> > -	struct dwc3_qcom *qcom = platform_get_drvdata(pdev);
> > -	struct device *dev = &pdev->dev;
> >  	int i;
> >
> > -	of_platform_depopulate(dev);
> > +	of_platform_depopulate(qcom->dev);
> >
> >  	for (i = qcom->num_clocks - 1; i >= 0; i--) {
> >  		clk_disable_unprepare(qcom->clks[i]);
> > @@ -807,12 +805,27 @@ static int dwc3_qcom_remove(struct 
> > platform_device *pdev)
> >  	dwc3_qcom_interconnect_exit(qcom);
> >  	reset_control_assert(qcom->resets);
> >
> > -	pm_runtime_allow(dev);
> > -	pm_runtime_disable(dev);
> > +	pm_runtime_allow(qcom->dev);
> > +	pm_runtime_disable(qcom->dev);
> > +}
>
> you can make the changes smaller by adding:
>
> 	struct device *dev = qcom->dev;
>
> The nothing else needs to change in this function ;-)

I will do this in next version