From: Felipe Balbi <balbi@kernel.org>
To: Vicente Bergas <vicencb@gmail.com>, 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: Wed, 23 Oct 2019 09:31:21 +0300 [thread overview]
Message-ID: <877e4wj7ly.fsf@gmail.com> (raw)
In-Reply-To: <0edb55d4-3bad-47ac-9d29-8d994d182e67@gmail.com>
[-- Attachment #1.1: Type: text/plain, Size: 3709 bytes --]
Hi,
(sorry for the long delay)
Vicente Bergas <vicencb@gmail.com> writes:
> 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?
I meant something like this:
diff --git a/drivers/usb/dwc3/dwc3-of-simple.c b/drivers/usb/dwc3/dwc3-of-simple.c
index bdac3e7d7b18..e64754be47b4 100644
--- a/drivers/usb/dwc3/dwc3-of-simple.c
+++ b/drivers/usb/dwc3/dwc3-of-simple.c
@@ -110,12 +110,9 @@ static int dwc3_of_simple_probe(struct platform_device *pdev)
return ret;
}
-static int dwc3_of_simple_remove(struct platform_device *pdev)
+static void __dwc3_of_simple_teardown(struct dwc3_of_simple *simple)
{
- struct dwc3_of_simple *simple = platform_get_drvdata(pdev);
- struct device *dev = &pdev->dev;
-
- of_platform_depopulate(dev);
+ of_platform_depopulate(simple->dev);
clk_bulk_disable_unprepare(simple->num_clocks, simple->clks);
clk_bulk_put_all(simple->num_clocks, simple->clks);
@@ -126,13 +123,27 @@ static int dwc3_of_simple_remove(struct platform_device *pdev)
reset_control_put(simple->resets);
- pm_runtime_disable(dev);
- pm_runtime_put_noidle(dev);
- pm_runtime_set_suspended(dev);
+ pm_runtime_disable(simple->dev);
+ pm_runtime_put_noidle(simple->dev);
+ pm_runtime_set_suspended(simple->dev);
+}
+
+static int dwc3_of_simple_remove(struct platform_device *pdev)
+{
+ struct dwc3_of_simple *simple = platform_get_drvdata(pdev);
+
+ __dwc3_of_simple_teardown(simple);
return 0;
}
+static void dwc3_of_simple_shutdown(struct platform_device *pdev)
+{
+ struct dwc3_of_simple *simple = platform_get_drvdata(pdev);
+
+ __dwc3_of_simple_teardown(simple);
+}
+
static int __maybe_unused dwc3_of_simple_runtime_suspend(struct device *dev)
{
struct dwc3_of_simple *simple = dev_get_drvdata(dev);
@@ -190,6 +201,7 @@ MODULE_DEVICE_TABLE(of, of_dwc3_simple_match);
static struct platform_driver dwc3_of_simple_driver = {
.probe = dwc3_of_simple_probe,
.remove = dwc3_of_simple_remove,
+ .shutdown = dwc3_of_simple_shutdown,
.driver = {
.name = "dwc3-of-simple",
.of_match_table = of_dwc3_simple_match,
Can you make sure it works as you intended?
--
balbi
[-- Attachment #1.2: signature.asc --]
[-- Type: application/pgp-signature, Size: 832 bytes --]
[-- Attachment #2: Type: text/plain, Size: 176 bytes --]
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-10-23 6:31 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
2019-10-23 6:31 ` Felipe Balbi [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=877e4wj7ly.fsf@gmail.com \
--to=balbi@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=gregkh@linuxfoundation.org \
--cc=heiko@sntech.de \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-rockchip@lists.infradead.org \
--cc=linux-usb@vger.kernel.org \
--cc=marc.zyngier@arm.com \
--cc=mbrugger@suse.com \
--cc=robin.murphy@arm.com \
--cc=vicencb@gmail.com \
--cc=will.deacon@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).