Re: [PATCH 3/6] xhci: probe phy before add usb_hcd

[Roger Quadros]

Mathias.

On 01/06/15 18:17, Mathias Nyman wrote:
> On 01.06.2015 17:52, Yingjoe Chen wrote:
> > On Wed, 2015-05-27 at 07:18 -0500, Felipe Balbi wrote:
> > > On Wed, May 27, 2015 at 07:48:00PM +0800, chunfeng.yun@xxxxxxxxxxxx wrote:
> > > > From: Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx>
> > > >
> > > > find the phy driver before add primary usb_hcd to avoid acessing
> > > > xHCI register which may hangup the system when the phy is not loaded
> > > > yet and the related powers or clocks put in phy driver are not
> > > > enabled.
> > >
> > > it seems like the same clock is needed by PHY and XHCI. This patch looks
> > > incorrect.
> >
> >
> > Hi,
> >
> > I agree that the driver should enable clock it used by itself and not
> > depends on init order. This should be fixed.
> >
> > But in general, I think it make sense to only add hcd after all required
> > resource are ready. At least it remove unnecessary calls to
> > usb_add_hcd/usb_remove_hcd. Is it better if the commit message is
> > changed to something like the below?
> >
> > Currently xhci_plat_probe() call usb_add_hcd before trying to init the
> > phy. However if the phy is not ready at the moment, it have to remove
> > the hcd and probe again later
> >
> > Change the init order so we only add hcd when all required resource are
> > ready.
> Hi
>
> Rogers Quadros patchseries that changes how HCDs are created and added for
> xhci-plat was just sent forward. It first creates both HCDs, then adds them.
>
> Doesn't usb_add_hcd() as it's first task take care of the PHYs?
> I'm hoping to remove that part completely from xhci-plat.c but haven't
> looked into it properly yet.

usb_add_hcd() does

        if (IS_ENABLED(CONFIG_USB_PHY) && !hcd->usb_phy) {
                struct usb_phy *phy = usb_get_phy_dev(hcd->self.controller, 0);
...
        if (IS_ENABLED(CONFIG_GENERIC_PHY) && !hcd->phy) {
                struct phy *phy = phy_get(hcd->self.controller, "usb");
...

but xhci-plat.c does
	hcd->usb_phy = devm_usb_get_phy_by_phandle(&pdev->dev, "usb-phy", 0);


So there needs to be some alignment.

cheers,
-roger
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