Re: [PATCH v2, 3/3] usb: dwc3: core: Workaround for CSR read timeout

[joswang]

On Thu, Jun 6, 2024 at 9:29 AM Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> wrote:
>
> On Tue, Jun 04, 2024, joswang wrote:
> > On Tue, Jun 4, 2024 at 8:07 AM Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> wrote:
> > >
> > > On Mon, Jun 03, 2024, joswang wrote:
> > > > From: joswang <joswang@xxxxxxxxxx>
> > > >
> > > > DWC31 version 2.00a have an issue that would cause
> > > > a CSR read timeout When CSR read coincides with RAM
> > > > Clock Gating Entry.
> > >
> > > Do you have the STAR issue number?
> > >
> > Thanks for reviewing the code.
> > The STAR number provided by Synopsys is 4846132.
> > Please help review further.
>
> I've confirmed internally. As you have noted, this applies to DWC_usb31
> v2.00a for host mode only and DRD mode operating as host.
>
> >
> > > >
> > > > This workaround solution disable Clock Gating, sacrificing
> > > > power consumption for normal operation.
> > > >
> > > > Signed-off-by: joswang <joswang@xxxxxxxxxx>
> > > > ---
> > > >  drivers/usb/dwc3/core.c | 23 +++++++++++++++++++++++
> > > >  1 file changed, 23 insertions(+)
> > > >
> > > > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> > > > index 3a8fbc2d6b99..1df85c505c9e 100644
> > > > --- a/drivers/usb/dwc3/core.c
> > > > +++ b/drivers/usb/dwc3/core.c
> > > > @@ -978,11 +978,22 @@ static void dwc3_core_setup_global_control(struct dwc3 *dwc)
> > > >                *
> > > >                * STAR#9000588375: Clock Gating, SOF Issues when ref_clk-Based
> > > >                * SOF/ITP Mode Used
>
> Since there's another STAR, let's split the if-else case separately and
> provide the comments separately.
>
OK
> > > > +              *
> > > > +              * WORKAROUND: DWC31 version 2.00a have an issue that would
>
> Can we use the full name DWC_usb31 instead of DWC31.
>
Subsequent V3 versions use DWC_usb31
> > > > +              * cause a CSR read timeout When CSR read coincides with RAM
> > > > +              * Clock Gating Entry.
> > > > +              *
> > > > +              * This workaround solution disable Clock Gating, sacrificing
> > > > +              * power consumption for normal operation.
> > > >                */
> > > >               if ((dwc->dr_mode == USB_DR_MODE_HOST ||
> > > >                               dwc->dr_mode == USB_DR_MODE_OTG) &&
> > > >                               DWC3_VER_IS_WITHIN(DWC3, 210A, 250A))
> > > >                       reg |= DWC3_GCTL_DSBLCLKGTNG | DWC3_GCTL_SOFITPSYNC;
> > > > +             else if ((dwc->dr_mode == USB_DR_MODE_HOST ||
> > > > +                             dwc->dr_mode == USB_DR_MODE_OTG) &&
>
> There's no OTG mode for DWC_usb31. Let's enable this workaround if the
> HW mode is not DWC_GHWPARAMS0_MODE_GADGET.
>
> > > > +                             DWC3_VER_IS(DWC31, 200A))
> > > > +                     reg |= DWC3_GCTL_DSBLCLKGTNG;
> > > >               else
> > > >                       reg &= ~DWC3_GCTL_DSBLCLKGTNG;
> > > >               break;
> > > > @@ -992,6 +1003,18 @@ static void dwc3_core_setup_global_control(struct dwc3 *dwc)
> > > >                * will work. Device-mode hibernation is not yet implemented.
> > > >                */
> > > >               reg |= DWC3_GCTL_GBLHIBERNATIONEN;
> > > > +
> > > > +             /*
> > > > +              * WORKAROUND: DWC31 version 2.00a have an issue that would
> > > > +              * cause a CSR read timeout When CSR read coincides with RAM
> > > > +              * Clock Gating Entry.
> > > > +              *
> > > > +              * This workaround solution disable Clock Gating, sacrificing
> > > > +              * power consumption for normal operation.
> > > > +              */
> > > > +             if ((dwc->dr_mode == USB_DR_MODE_HOST ||
> > > > +                  dwc->dr_mode == USB_DR_MODE_OTG) && DWC3_VER_IS(DWC31, 200A))
> > > > +                     reg |= DWC3_GCTL_DSBLCLKGTNG;
> > > >               break;
> > > >       default:
> > > >               /* nothing */
> > > > --
> > > > 2.17.1
> > > >
> > >
>
> We have the same checks and comments here. Can we refactor?
> Perhaps something this?
>
> power_opt = DWC3_GHWPARAMS1_EN_PWROPT(dwc->hwparams.hwparams1);
> switch (power_opt) {
>     ...
> }
>
> /*
>  * <comment>
>  */
> if (power_opt != DWC3_GHWPARAMS1_EN_PWROPT_NO) {
> }
>
>
> Thanks,
> Thinh

Thank you for your valuable suggestions.I can refactor according to
your suggestion.
Do I need to submit a V3 version patch separately, or should I submit
a V3 version patch together with other cases?

Thanks,
Jos Wang