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Subject: Re: Regarding usb dwc3 core shutdown callback
To:     Felipe Balbi <balbi@kernel.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>
References: <e34c8e16-6521-c6e4-f3ed-9d8520d4ece2@codeaurora.org>
 <87bl63yqq8.fsf@kernel.org>
 <eb975a76-1482-f502-4dc1-7993cc3f30d0@codeaurora.org>
 <87eeaga39m.fsf@kernel.org>
From:   Sandeep Maheswaram <sanm@codeaurora.org>
Message-ID: <7a6bf94b-91cd-15d5-dd9c-798e7a927727@codeaurora.org>
Date:   Mon, 30 Aug 2021 09:48:16 +0530
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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-email-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.elisei@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@nxp.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.  Anything we can do 
apart from kexec?