From: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Sandeep Maheswaram <sanm@codeaurora.org>,
Felipe Balbi <balbi@kernel.org>,
Stephen Boyd <swboyd@chromium.org>,
Doug Anderson <dianders@chromium.org>,
Matthias Kaehlcke <mka@chromium.org>,
linux-arm-msm@vger.kernel.org, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org,
Manu Gautam <mgautam@codeaurora.org>
Subject: Re: [PATCH v1] usb: dwc3: core: Add shutdown callback for dwc3
Date: Tue, 30 Mar 2021 15:25:58 +0530 [thread overview]
Message-ID: <d2348b758fa57acf53885b67f066e0a1@codeaurora.org> (raw)
In-Reply-To: <YGLqXI8HOaOrMq1B@kroah.com>
On 2021-03-30 14:37, Greg Kroah-Hartman wrote:
> On Tue, Mar 30, 2021 at 02:12:04PM +0530, Sandeep Maheswaram wrote:
>>
>> On 3/26/2021 7:07 PM, Greg Kroah-Hartman wrote:
>> > On Wed, Mar 24, 2021 at 12:57:32AM +0530, Sandeep Maheswaram wrote:
>> > > This patch adds a shutdown callback to USB DWC core driver to ensure that
>> > > it is properly shutdown in reboot/shutdown path. This is required
>> > > where SMMU address translation is enabled like on SC7180
>> > > SoC and few others. If the hardware is still accessing memory after
>> > > SMMU translation is disabled as part of SMMU shutdown callback in
>> > > system reboot or shutdown path, then IOVAs(I/O virtual address)
>> > > which it was using will go on the bus as the physical addresses which
>> > > might result in unknown crashes (NoC/interconnect errors).
>> > >
>> > > Previously this was added in dwc3 qcom glue driver.
>> > > https://patchwork.kernel.org/project/linux-arm-msm/list/?series=382449
>> > > But observed kernel panic as glue driver shutdown getting called after
>> > > iommu shutdown. As we are adding iommu nodes in dwc core node
>> > > in device tree adding shutdown callback in core driver seems correct.
>> > So shouldn't you also remove this from the qcom glue driver at the same
>> > time? Please submit both as a patch series.
>> >
>> > thanks,
>> >
>> > greg k-h
>>
>> Hi Greg,
>>
>> The qcom glue driver patch is not merged yet. I have just mentioned
>> for it for reference.
>
> You know that we can not add callbacks for no in-kernel user, so what
> good is this patch for now?
>
What in-kernel user? Since when does shutdown callback need an in-kernel
user? When you reboot or shutdown a system, it gets called. The reason
why the shutdown callback is needed is provided in the commit text.
Confused,
Sai Prakash Ranjan
--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
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of Code Aurora Forum, hosted by The Linux Foundation
next prev parent reply other threads:[~2021-03-30 9:56 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-23 19:27 [PATCH v1] usb: dwc3: core: Add shutdown callback for dwc3 Sandeep Maheswaram
2021-03-24 3:31 ` Stephen Boyd
2021-03-25 5:05 ` Sandeep Maheswaram
2021-03-24 9:39 ` Sergei Shtylyov
2021-03-26 13:37 ` Greg Kroah-Hartman
2021-03-30 8:42 ` Sandeep Maheswaram
2021-03-30 9:07 ` Greg Kroah-Hartman
2021-03-30 9:55 ` Sai Prakash Ranjan [this message]
2021-03-30 11:16 ` Greg Kroah-Hartman
2021-03-30 12:48 ` Sai Prakash Ranjan
2021-03-30 13:32 ` Greg Kroah-Hartman
2021-03-31 7:07 ` Sai Prakash Ranjan
2021-04-08 4:52 ` Sandeep Maheswaram
2021-04-08 7:29 ` Greg Kroah-Hartman
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