Subject: Re: kexec on rk3399

From: Felipe Balbi <[email-masked]>
Date: Wed, 14 Aug 2019 16:06:04 +0300

Hi,

Vicente Bergas <[email-masked]> 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.
>>
>> It turns out that kexec has never worked reliably on this platform,
>> i was just lucky until recently.
>>
>> Please, can you provide some directions on how to debug the issue?
>
> Thank you all for your suggestions on where the issue could be.
>
> 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.
>
> The workaround is:
> --- a/drivers/usb/dwc3/dwc3-of-simple.c
> +++ b/drivers/usb/dwc3/dwc3-of-simple.c
> @@ -133,6 +133,13 @@
>  	return 0;
>  }
>  
> +static void dwc3_of_simple_shutdown(struct platform_device *pdev)
> +{
> +	struct dwc3_of_simple *simple = platform_get_drvdata(pdev);
> +
> +	reset_control_assert(simple->resets);
> +}
> +
>  static int __maybe_unused dwc3_of_simple_runtime_suspend(struct device 
> *dev)
>  {
>  	struct dwc3_of_simple	*simple = dev_get_drvdata(dev);
> @@ -190,6 +197,7 @@
>  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,
>
> 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.

-- 
balbi
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