Re: [RESEND PATCH v2 1/7] usb: xhci: plat: Fix suspend/resume when the optional clk exists

From: Jisheng Zhang
Date: Wed Apr 27 2016 - 01:50:53 EST


Dear Felipe,

On Wed, 27 Apr 2016 08:25:38 +0300 Felipe Balbi wrote:

> Hi,
>
> (since you're fixing somebody else's commit, it's nice to Cc authors)
>
> Jisheng Zhang <jszhang@xxxxxxxxxxx> writes:
> > Commit 4718c1774051 ("usb: host: xhci-plat: add clock support") adds
> > optional clk support, but it forgets to prepare/disable and
> ^^^^^^^^^^^^^^^
> prepare/enable ?
>
> > enable/unprepare the clk in the resume/suspend path. This path fixes
> ^^^^^^^^^^^^^^^^ ^^^^
> disable/unprepare ? patch
>
> > this issue by adding missing clk related calls.
>
> frankly, I'm not sure this patch is entirely correct. At minimum, it's
> not necessarily a bug fix. Original commit had no intent in gating
> clocks during suspend/resume and, IMHO, that might not be what *all*
> XHCI implementations want, though I'm not entirely sure.

Thanks for the hint. Indeed, that's not all xhci-plat users want. I'll drop
this patch in v3.

Thanks a lot for the review,
Jisheng

>
> > Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxxx>
> > Fixes: 4718c1774051 ("usb: host: xhci-plat: add clock support")
>
> Assuming this is, indeed, a fix; you need to Cc stable here. Just add:
>
> Cc: <stable@xxxxxxxxxxxxxxx> # v3.16+
>
> > ---
> > drivers/usb/host/xhci-plat.c | 14 +++++++++++++-
> > 1 file changed, 13 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
> > index 474b5fa..8cb46cb 100644
> > --- a/drivers/usb/host/xhci-plat.c
> > +++ b/drivers/usb/host/xhci-plat.c
> > @@ -295,6 +295,7 @@ static int xhci_plat_remove(struct platform_device *dev)
> > #ifdef CONFIG_PM_SLEEP
> > static int xhci_plat_suspend(struct device *dev)
> > {
> > + int ret;
>
> this would look neater after hcd and xhci declarations below
>
> > struct usb_hcd *hcd = dev_get_drvdata(dev);
> > struct xhci_hcd *xhci = hcd_to_xhci(hcd);
> >
> > @@ -306,14 +307,25 @@ static int xhci_plat_suspend(struct device *dev)
> > * reconsider this when xhci_plat_suspend enlarges its scope, e.g.,
> > * also applies to runtime suspend.
> > */
> > - return xhci_suspend(xhci, device_may_wakeup(dev));
> > + ret = xhci_suspend(xhci, device_may_wakeup(dev));
> > + if (ret)
> > + return ret;
> > +
> > + clk_disable_unprepare(xhci->clk);
> > +
> > + return ret;
> > }
> >
> > static int xhci_plat_resume(struct device *dev)
> > {
> > + int ret;
>
> ditto
>
> > struct usb_hcd *hcd = dev_get_drvdata(dev);
> > struct xhci_hcd *xhci = hcd_to_xhci(hcd);
> >
> > + ret = clk_prepare_enable(xhci->clk);
> > + if (ret)
> > + return ret;
> > +
> > return xhci_resume(xhci, 0);
> > }
> >
> > --
> > 2.8.1
> >
> > --
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