Re: [PATCH v3 3/4] usb: dwc3: Add device property sgl-trb-cache-size-quirk

[Jun Li <lijun.kernel@gmail.com>]

Thinh Nguyen <Thinh.Nguyen@synopsys.com> 于2020年8月4日周二 上午8:46写道：
>
> Hi Rob,
>
> Tejas Joglekar wrote:
> > Hello Rob,
> > On 7/21/2020 10:27 PM, Tejas Joglekar wrote:
> >> Hello,
> >>
> >> On 7/21/2020 3:17 PM, Felipe Balbi wrote:
> >>> Tejas Joglekar <Tejas.Joglekar@synopsys.com> writes:
> >>>
> >>>> Hi Rob,
> >>>>
> >>>> On 7/6/2020 12:13 PM, Felipe Balbi wrote:
> >>>>> Hi,
> >>>>>
> >>>>> Tejas Joglekar <Tejas.Joglekar@synopsys.com> writes:
> >>>>>>> @@ -95,6 +95,10 @@ int dwc3_host_init(struct dwc3 *dwc)
> >>>>>>>         if (dwc->usb2_lpm_disable)
> >>>>>>>                 props[prop_idx++] = PROPERTY_ENTRY_BOOL("usb2-lpm-disable");
> >>>>>>>
> >>>>>>> +       if (dwc->sgl_trb_cache_size_quirk)
> >>>>>>> +               props[prop_idx++] =
> >>>>>>> +                       PROPERTY_ENTRY_BOOL("sgl-trb-cache-size-quirk");
> >>>>>>> +
> >>>>>>>         /**
> >>>>>>>          * WORKAROUND: dwc3 revisions <=3.00a have a limitation
> >>>>>>>          * where Port Disable command doesn't work.
> >>>>>>>
> >>>>>> Does this implementation looks good to you? Rob has some concerned over the DT entries,
> >>>>>> you suggested using compatible string with this quirk addition.
> >>>>>> Can you please brief about how you would like to have this quirk implemented?
> >>>>>> I can send the updated patch. My patch series is pending for merge just because of the
> >>>>>> DT and quirk issue. Can you please help?
> >>>>> Yeah, you need to get into an agreement with Rob :-) I don't mind having
> >>>>> extra DT flags for things which can't be detected in runtime, Rob
> >>>>> disagrees.
> >>>>>
> >>>> The compatible string is not suitable option as it does not work with platform drivers
> >>>> with PCI based system. Also Synopsys controllers IP version register is not visible to xhci
> >>>> driver and hence we don't have separate compatible string for each Synopsys version on the
> >>>> xhci driver side.
> >>>> Due to which I depend on DT flag addition for the quirk. Can we add these DT flags and quirk?
> >>> As I said, I'm well aware of the situation regarding usage of compatible
> >>> strings and the fact that dwc3 must work on PCI and non-PCI systems (I
> >>> wrote the thing as it is after all). The person blocking new quirk flags
> >>> is Rob, not me. You need to convince Rob that this is the way to go.
> >>>
> >> @Felipe: Sorry for confusion if any, previous mail was intended for Rob asking about his approval.
> >>
> >>> Rob, ball's in your court. Sorry.>
> >> @Rob: As I and Felipe have mentioned before, it is very much necessary to have quirk flags
> >> for the current changes as compatible string would not be a solution for PCI and non-PCI
> >> systems. Can you please approve this change ? If you have any concern about naming or any
> >> other thing, please let us know.
> >>
> > Can you please comment?
> >
> > Thanks & Regards,
> > Tejas Joglekar
> >
> >
>
> Can you help provide pointers and changes that Tejas can make to help
> bring this issue to conclusion?

We really need a direction to handle growing dwc3 quirks/flags as dwc3
is widly used,
I have a patchset also pending there after tried both property[1] and
platform data[2].

[1] https://www.spinics.net/lists/linux-usb/msg196055.html
[2] https://www.spinics.net/lists/arm-kernel/msg824995.html

thanks
Li Jun
>
> Thanks,
> Thinh