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From:   Vicente Bergas <vicencb@gmail.com>
To:     Felipe Balbi <balbi@kernel.org>
Cc:     Robin Murphy <robin.murphy@arm.com>,
        Heiko Stuebner <heiko@sntech.de>,
        Will Deacon <will.deacon@arm.com>,
        Marc Zyngier <marc.zyngier@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Matthias Brugger <mbrugger@suse.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        <linux-usb@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-rockchip@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>
Subject: Re: kexec on rk3399
Date:   Wed, 14 Aug 2019 15:15:02 +0200
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On Wednesday, August 14, 2019 3:06:04 PM CEST, Felipe Balbi wrote:
> Hi,
>
> Vicente Bergas <vicencb@gmail.com> writes:
>> On Monday, July 22, 2019 4:31:27 PM CEST, Vicente Bergas wrote:
>>> Hi, i have been running linux on rk3399 booted with kexec fine until 5.2
>>> From 5.2 onwards, there are memory corruption issues as reported here:
>>> http://lkml.iu.edu/hypermail/linux/kernel/1906.2/07211.html
>>> kexec has been identified as the principal reason for the issues.
>>>=20
>>> It turns out that kexec has never worked reliably on this platform, ...
>>=20
>> Thank you all for your suggestions on where the issue could be.
>>=20
>> It seems that it was the USB driver.
>> Now using v5.2.8 booted with kexec from v5.2.8 with a workaround and
>> so far so good. It is being tested on the Sapphire board.
>>=20
>> The workaround is:
>> --- a/drivers/usb/dwc3/dwc3-of-simple.c
>> +++ b/drivers/usb/dwc3/dwc3-of-simple.c
>> @@ -133,6 +133,13 @@
>>  =09return 0;
>>  }
>> =20
>> +static void dwc3_of_simple_shutdown(struct platform_device *pdev)
>> +{
>> +=09struct dwc3_of_simple *simple =3D platform_get_drvdata(pdev);
>> +
>> +=09reset_control_assert(simple->resets);
>> +}
>> +
>>  static int __maybe_unused dwc3_of_simple_runtime_suspend(struct device=20=

>> *dev)
>>  {
>>  =09struct dwc3_of_simple=09*simple =3D dev_get_drvdata(dev);
>> @@ -190,6 +197,7 @@
>>  static struct platform_driver dwc3_of_simple_driver =3D {
>>  =09.probe=09=09=3D dwc3_of_simple_probe,
>>  =09.remove=09=09=3D dwc3_of_simple_remove,
>> +=09.shutdown=09=3D dwc3_of_simple_shutdown,
>>  =09.driver=09=09=3D {
>>  =09=09.name=09=3D "dwc3-of-simple",
>>  =09=09.of_match_table =3D of_dwc3_simple_match,
>>=20
>> If this patch is OK after review i can resubmit it as a pull request.
>
> not a pull request, just send a patch using git send-email
>
>> Should a similar change be applied to drivers/usb/dwc3/core.c ?
>
> Is it necessary? We haven't had any bug reports regarding that. Also, if
> we have reset control support in the core driver, why do we need it in
> of_simple? Seems like of_simple could just rely on what core does.

the workaround has been tested patching only core.c with
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1561,6 +1561,13 @@
 =09return 0;
 }
=20
+static void dwc3_shutdown(struct platform_device *pdev)
+{
+=09struct dwc3 *dwc =3D platform_get_drvdata(pdev);
+
+=09reset_control_assert(dwc->reset);
+}
+
 #ifdef CONFIG_PM
 static int dwc3_core_init_for_resume(struct dwc3 *dwc)
 {
@@ -1866,6 +1873,7 @@
 static struct platform_driver dwc3_driver =3D {
 =09.probe=09=09=3D dwc3_probe,
 =09.remove=09=09=3D dwc3_remove,
+=09.shutdown=09=3D dwc3_shutdown,
 =09.driver=09=09=3D {
 =09=09.name=09=3D "dwc3",
 =09=09.of_match_table=09=3D of_match_ptr(of_dwc3_match),

and leaving dwc3-of-simple.c as is, the issue persisted.

Regards,
  Vicen=C3=A7.