[RFT PATCH v1 1/5] Revert "usb: ehci-hcd: Keep async schedule running"

Marek Vasut
2020-03-24T15:07:20Z

On 3/24/20 8:06 AM, Lukasz Majewski wrote:
> Hi Marek,

Hi,

[...]

>>>> You should probably figure out why this doesn't work first and then
>>>> add fixes on top.
>>>
>>> Haven't you seen such problem during code development on your setup
>>> when developing this patch?
>>
>> During the development of the patch, I don't remember, sorry. I most
>> certainly saw various failure modes, however those should not be
>> present mainline.
>
> The issue is that the qhtoken is not updated at all.
>
> Maybe you remember - is Linux using async setup by default (as
> introduced in SHA1: 02b0e1a36c5bc20174299312556ec4e266872bd6) ?

If I recall correctly, it is using async schedule for bulk transfers.
But the code is available, so you can double-check that.

>> I tested this patch with the problematic USB sticks on R-Car Gen3 and
>> with SMSC95xx USB ethernet adapter last weekend and I didn't see a
>> problem.
>
> Ok.
>
> For i.MX6Q:
> The SHA1: 02b0e1a36c5bc20174299312556ec4e266872bd6 patch causes the
> iMX6Q to fail after a few minutes of testing. General in i.MX6Q the
> usb is NOT robust at all.
>
> For i.MX53:
> With patch 02b0e1a36c5bc20174299312556ec4e266872bd6 applied it also
> breaks after a few minutes.

So on CI HDRC , there is some difference in behavior. That is what you
need to find and fix then.

> With this patch series applied it works for 2 days now without any
> issue.

Except performance is totally degraded and there is still no clear
explanation _why_ any of these patches are needed and/or whether doing
write to a block device with these patches may cause data corruption.