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From:   Felipe Balbi <balbi@kernel.org>
To:     Sandeep Maheswaram <sanm@codeaurora.org>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Mathias Nyman <mathias.nyman@intel.com>,
        linux-arm-msm@vger.kernel.org, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Pratham Pratap <prathampratap@codeaurora.org>,
        Jack Pham <jackp@codeaurora.org>,
        Stephen Boyd <swboyd@chromium.org>,
        Matthias Kaehlcke <mka@chromium.org>,
        Doug Anderson <dianders@chromium.org>
Subject: Re: Regarding usb dwc3 core shutdown callback
Date:   Mon, 30 Aug 2021 07:45:57 +0300
In-reply-to: <7a6bf94b-91cd-15d5-dd9c-798e7a927727@codeaurora.org>
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Sandeep Maheswaram <sanm@codeaurora.org> writes:

> Hi,
>
> On 8/26/2021 4:13 PM, Felipe Balbi wrote:
>> Hi,
>>
>> Sandeep Maheswaram <sanm@codeaurora.org> writes:
>>>> (why isn't this email plain/text? Content Type was set to multipart
>>>> alternative, please configure your email client correctly :-)
>>>>
>>>> While at that, also make sure to break lines at 80-columns)
>>>>
>>>> Sandeep Maheswaram <sanm@codeaurora.org> writes:
>>>>> Hi,
>>>>>
>>>>> Earlier I have posted the patch for usb dwc3 core shutdown callback
>>>>>
>>>>> https://lore.kernel.org/linux-arm-msm/1618380209-20114-1-git-send-ema=
il-sanm@codeaurora.org/
>>>>>
>>>>> and it was reverted due to issues.
>>>> Right, as should be expected when we find regressions
>>>>
>>>>> https://lore.kernel.org/linux-usb/20210603151742.298243-1-alexandru.e=
lisei@arm.com/
>>>>>
>>>>> As we already have shutdown callback in xhci plat driver where we halt
>>>>> the controller, so there will be no transactions with usb devices.
>>>>>
>>>>> https://lore.kernel.org/linux-usb/20200306092328.41253-1-ran.wang_1@n=
xp.com/
>>>>>
>>>>> So I think dwc3 core shutdown may not be required at least when we are
>>>>> using host mode. Let me know your opinion about this.
>>>> If that's the case, then sure. Please validate the condition, though,
>>>> and kindly report back on your findings
>>> I have enabled couple of logs in shutdown path and see no URBs
>>> enqueued after xhci shut down.
>>>
>>> Hope this is enough for validation . Please suggest if anything more I
>>> could do.
>> how about writing a little script to kexec into another kernel for a few
>> hundred iterations and make sure things still work after all that?
>
> Currently kexec is not supported on qcom devices.=C2=A0 Anything we can do
> apart from kexec?

Sure about that? I've been using kexec with 8150 for quite a while.

--=20
balbi