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From: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
To: Roman Kapl <roman.kapl@sysgo.com>,
	Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
	Roman Kapl <rka@sysgo.com>,
	"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Felipe Balbi <balbi@kernel.org>
Subject: Re: [PATCH] usb: dwc3: reset the address and run_stop on init
Date: Mon, 9 Sep 2019 17:54:37 +0000	[thread overview]
Message-ID: <9806c612-506d-eac1-81a7-13bcc8cd8a39@synopsys.com> (raw)
In-Reply-To: <5a6a8d61-1ccf-9731-0b80-da783636970f@sysgo.com>

Hi,

Roman Kapl wrote:
> Hello,
>
> On 9/5/19 8:57 PM, Thinh Nguyen wrote:
>> Hi,
>>
>> Roman Kapl wrote:
>>> The address should be set to zero during reset according to the
>>> documentation.
>>
>> That is for usb reset and not core soft reset, and dwc3 already handles
>> that case.
>
> I thought that core soft reset is part of the USB reset (it is done 
> during the init, right?).

A soft reset is done during device power-on init. It's not part of the 
USB reset.

>
>>
>>> Clearing RunStop ensures that the host disconnects from
>>> the device (it was not cleared by CSFTRST, at least on ls1043).
>>>
>>> This allows the dwc3 to properly initialize even if the previous
>>> driver did not shutdown the device (e.g. when using virtualization).
>>
>> This sounds like a workaround to some issue that the function driver did
>> not handle.
>
> I am using the ACM function driver. However, as I said, the issue 
> arises only when the dwc3 driver is in a guest OS that is rebooted 
> (even if the reboot is initiated from within the guest OS, not a hard 
> reset).

Check why it wasn't de-initialized on reboot. Also please describe what 
problem you saw in the patch.

>
> Maybe this is out of scope for Linux, trying to 'clean up' after the 
> previous driver?
>
> Thank you, Roman Kapl
>

BR,
Thinh

      reply	other threads:[~2019-09-09 17:55 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-05  9:51 [PATCH] usb: dwc3: reset the address and run_stop on init Roman Kapl
2019-09-05 18:57 ` Thinh Nguyen
2019-09-09  9:32   ` Roman Kapl
2019-09-09 17:54     ` Thinh Nguyen [this message]

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