From: Vicente Bergas <vicencb@gmail.com>
To: Felipe Balbi <balbi@kernel.org>, Robin Murphy <robin.murphy@arm.com>
Cc: Matthias Brugger <mbrugger@suse.com>,
Heiko Stuebner <heiko@sntech.de>,
MarcZyngier <marc.zyngier@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
linux-usb@vger.kernel.org, Will Deacon <will.deacon@arm.com>,
linux-rockchip@lists.infradead.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] usb: dwc3: Add shutdown to platform_driver
Date: Mon, 09 Sep 2019 17:07:24 +0200 [thread overview]
Message-ID: <0edb55d4-3bad-47ac-9d29-8d994d182e67@gmail.com> (raw)
In-Reply-To: <645526b8-bfed-4cc6-9500-1843c5fe0da9@gmail.com>
On Tuesday, August 27, 2019 2:16:20 PM CEST, Vicente Bergas wrote:
> On Tuesday, August 27, 2019 1:53:04 PM CEST, Felipe Balbi wrote:
>> Hi,
>>
>> Vicente Bergas <vicencb@gmail.com> writes:
>>> On Saturday, August 17, 2019 7:41:40 PM CEST, Vicente Bergas wrote:
>>>> Otherwise the device keeps writing to memory after kexec and disturbs
>>>> the next kernel.
> ...
>>
>> why don't you just have shutdown use the same exact function as remove?
>> Frankly, though, I still don't fully understand what's going wrong
>> here. Why is the device still alive during kexec?
>>
>> cheers
>
> Hi Felipe,
> the remove and shutdown functions have different prototypes, so
> shutdown is wrapping remove.
> Would it be preferable to cast remove as shutdown?
>
> The issue with kexec is that the device is being used during the livetime
> of the first kernel. When the first kernel executes kexec it calls the
> shutdown function of drivers (instead of remove). Because of this the dwc3
> device keeps doing things like DMA.
> While the second kernel is taking over, it gets its memory corrupted with
> such DMA accesses from the device. When the second kernel reaches the point
> of taking over the dwc3 device, re-initializes it, but it is already too
> late. Still worse, if the second kernel did not have the dwc3 driver, it
> would get endless memory corruptions.
> All in all, devices that can do DMA need to stop doing it on shutdown.
>
> Regards,
> Vicenç.
Hi,
please, can you provide some feedback on this?
Regards,
Vicenç.
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next prev parent reply other threads:[~2019-09-09 15:07 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-22 14:31 kexec on rk3399 Vicente Bergas
2019-07-22 14:46 ` Will Deacon
2019-07-22 16:08 ` Vicente Bergas
2019-07-22 14:47 ` Matthias Brugger
2019-07-22 16:56 ` Vicente Bergas
2019-07-22 14:54 ` Marc Zyngier
2019-07-22 17:05 ` Vicente Bergas
2019-07-22 17:35 ` Robin Murphy
2019-07-22 18:53 ` Vicente Bergas
2019-07-23 13:32 ` Robin Murphy
2019-08-14 12:53 ` Vicente Bergas
2019-08-14 13:06 ` Felipe Balbi
2019-08-14 13:15 ` Vicente Bergas
2019-08-15 6:00 ` Felipe Balbi
2019-08-14 13:12 ` Robin Murphy
2019-08-15 1:15 ` Vicente Bergas
2019-08-15 6:06 ` Felipe Balbi
2019-08-15 11:09 ` Robin Murphy
2019-08-17 17:41 ` [PATCH] usb: dwc3: Add shutdown to platform_driver Vicente Bergas
2019-08-27 11:45 ` Vicente Bergas
2019-08-27 11:53 ` Felipe Balbi
2019-08-27 12:16 ` Vicente Bergas
2019-09-09 15:07 ` Vicente Bergas [this message]
2019-10-23 6:31 ` Felipe Balbi
2019-10-24 12:15 ` Vicente Bergas
2019-10-25 10:25 ` Felipe Balbi
2019-10-25 10:42 ` Vicente Bergas
2019-09-19 11:36 ` Vicente Bergas
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