On Mon, Mar 29, 2021 at 3:15 PM Wesley Cheng [off-list ref] wrote:

On 3/19/2021 4:09 PM, Thinh Nguyen wrote:

quoted

Wesley Cheng wrote:

quoted

On 3/8/2021 10:33 PM, Wesley Cheng wrote:

quoted

On 3/8/2021 7:05 PM, Thinh Nguyen wrote:

quoted

Wesley Cheng wrote:

quoted

On 3/6/2021 3:41 PM, Thinh Nguyen wrote:

quoted

Wesley Cheng wrote:

quoted

On 1/8/2021 4:44 PM, Thinh Nguyen wrote:

quoted

Hi,

John Stultz wrote:

quoted

On Fri, Jan 8, 2021 at 4:26 AM Felipe Balbi [off-list ref] wrote:

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Hi,

John Stultz [off-list ref] writes:

quoted

From: Yu Chen <chenyu56@huawei.com>

Just resending this, as discussion died out a bit and I'm not
sure how to make further progress. See here for debug data that
was requested last time around:
  https://urldefense.com/v3/__https://lore.kernel.org/lkml/CALAqxLXdnaUfJKx0aN9xWwtfWVjMWigPpy2aqsNj56yvnbU80g@mail.gmail.com/__;!!A4F2R9G_pg!LNzuprAeg-O80SgolYkIkW4-ne-M-yLWCDUY9MygAIrQC398Z6gRJ9wnsnlqd3w$

With the current dwc3 code on the HiKey960 we often see the
COREIDLE flag get stuck off in __dwc3_gadget_start(), which
seems to prevent the reset irq and causes the USB gadget to
fail to initialize.

We had seen occasional initialization failures with older
kernels but with recent 5.x era kernels it seemed to be becoming
much more common, so I dug back through some older trees and
realized I dropped this quirk from Yu Chen during upstreaming
as I couldn't provide a proper rational for it and it didn't
seem to be necessary. I now realize I was wrong.

After resubmitting the quirk, Thinh Nguyen pointed out that it
shouldn't be a quirk at all and it is actually mentioned in the
programming guide that it should be done when switching modes
in DRD.

So, to avoid these !COREIDLE lockups seen on HiKey960, this
patch issues GCTL soft reset when switching modes if the
controller is in DRD mode.

Cc: Felipe Balbi <balbi@kernel.org>
Cc: Tejas Joglekar <redacted>
Cc: Yang Fei <redacted>
Cc: YongQin Liu <yongqin.liu@linaro.org>
Cc: Andrzej Pietrasiewicz <redacted>
Cc: Thinh Nguyen <redacted>
Cc: Jun Li <redacted>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
Signed-off-by: Yu Chen <chenyu56@huawei.com>
Signed-off-by: John Stultz <redacted>
---
v2:
* Rework to always call the GCTL soft reset in DRD mode,
  rather then using a quirk as suggested by Thinh Nguyen

v3:
* Move GCTL soft reset under the spinlock as suggested by
  Thinh Nguyen

Because this is such an invasive change, I would prefer that we get
Tested-By tags from a good fraction of the users before applying these
two changes.

I'm happy to reach out to folks to try to get that. Though I'm
wondering if it would be better to put it behind a dts quirk flag, as
originally proposed?
   https://urldefense.com/v3/__https://lore.kernel.org/lkml/20201021181803.79650-1-john.stultz@linaro.org/__;!!A4F2R9G_pg!LNzuprAeg-O80SgolYkIkW4-ne-M-yLWCDUY9MygAIrQC398Z6gRJ9wnRWITZfc$

That way folks can enable it for devices as they need?

Again, I'm not trying to force this in as-is, just mostly sending it
out again for discussion to understand what other approach might work.

thanks
-john

A quirk would imply something is broken/diverged from the design right?
But it's not the case here, and at least this is needed for HiKey960.
Also, I think Rob will be ok with not adding 1 more quirk to the dwc3
devicetree. :)

BR,
Thinh

Hi All,

Sorry for jumping in, but I checked the SNPS v1.90a databook, and that
seemed to remove the requirement for the GCTL.softreset before writing
to PRTCAPDIR.  Should we consider adding a controller version/IP check?

Hi Wesley,

From what I see in the v1.90a databook and others, the flow remains the
same. I need to check internally, but I'm not aware of the change.

Hi Thinh,

Hmmm, can you help check the register description for the PRTCAPDIR on
your v1.90a databook?  (Table 1-19 Fields for Register: GCTL (Continued)
Pg73)  When we compared the sequence in the description there to the
previous versions it removed the GCTL.softreset.  If it still shows up
on yours, then maybe my v1.90a isn't the final version?

Thanks
Wesley Cheng

Hi Wesley,

Actually your IP version type may use the newer flow. Can you print your
DWC3_VER_TYPE? I still need to verify internally to know which versions
need the update if any.

Thanks,
Thinh

Hi Thinh,

Sure, my DWC3_VER_TYPE output = 0x67612A2A

Thanks
Wesley Cheng

Hi Thinh,

Would you happen to have an update on the required sequence on the
version shared?  Sorry for pushing, but we just wanted to finalize on
it, since it does cause some functional issues w/o the soft reset in
place, and causes a crash if we have the GCTL.softreset.

Thanks
Wesley Cheng

Hi Wesley,

I'm still trying to get that info for you. The versions without
GCTL.softreset should be very new. The flow with GCTL.softreset should
work for all versions and should not cause functional impact. We can
create a change to optimize and remove GCTL.softreset for the newer
controller versions at a later time.

Since you and John Stultz have the setup that can be verified in the
real world. It would be great if John or you provide a tested patch(es)
to resolve this issue.

Thanks,
Thinh

Hi Thinh,

Thanks for the input as always.  I tested the GCTL.softreset change just
now, and it is working fine at least on my set up.

Not sure if we'd need input from other vendors as well to get this
change merged.

Did you test the original patch from this thread unchanged, or did you
have any modifications? If the latter, feel free to send it out and
I'll validate it on my side.

thanks
-john