Subject: Re: kexec on rk3399

From: Felipe Balbi <[email-masked]>
Date: Thu, 15 Aug 2019 09:00:16 +0300

Hi,

Vicente Bergas <[email-masked]> writes:
>> 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, ...
>>> 
>>> 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.
>
> 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 @@
>  	return 0;
>  }
>  
> +static void dwc3_shutdown(struct platform_device *pdev)
> +{
> +	struct dwc3 *dwc = platform_get_drvdata(pdev);
> +
> +	reset_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 = {
>  	.probe		= dwc3_probe,
>  	.remove		= dwc3_remove,
> +	.shutdown	= dwc3_shutdown,
>  	.driver		= {
>  		.name	= "dwc3",
>  		.of_match_table	= of_match_ptr(of_dwc3_match),
>
> and leaving dwc3-of-simple.c as is, the issue persisted.

That's because your reset controller is not passed to dwc3 core, only to
your glue layer.

-- 
balbi

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