Re: [PATCH 4/6] usb: cdns3: support power-off of controller when in host role

Théo Lebrun
2023-11-14T11:10:23Z

Hello,

On Tue Nov 14, 2023 at 9:38 AM CET, Peter Chen wrote:
> On 23-11-13 15:26:59, Théo Lebrun wrote:
> > The controller is not being reconfigured at resume. Change resume to
> > redo hardware config if quirk CDNS3_RESET_ON_RESUME is active.
>
> Current logic has power off judgement, see cdns3_controller_resume for
> detail.

Indeed! Thanks for the pointer. I had not noticed that, those patches
come from an older kernel which didn't have it. That'll make for less
changes; patches 4 & 5 can go away.

> > + if (cdns->pdata && cdns->pdata->quirks & CDNS3_RESET_ON_RESUME)
> > + cdns->xhci_plat_data->quirks |= XHCI_RESET_ON_RESUME | XHCI_SUSPEND_RESUME_CLKS;
> > +
>
> If you set this flag, how could you support the USB remote wakeup
> request? In that case, the USB bus does not expect re-enumeration.

We didn't support remote USB wakeup. Only S2R mattered in our case and
USB remote wakeup wasn't a possibility.

> > +static int cdns_host_resume(struct cdns *cdns, bool hibernated)
> > +{
> > + return cdns_drd_host_on(cdns);
>
> This one will redo if controller's power is off, please consider both
> on and power situation.

Clearly. Can see that at runtime.

Thanks for the review!

--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering