linux-kernel - Re: [RFT PATCH 1/2] usb: dwc2: Add a 10 ms delay to dwc2_core

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Date:	Fri, 4 Mar 2016 17:09:41 -0800
From:	Doug Anderson <dianders@...omium.org>
To:	Michael Niewoehner <linux@...ewoehner.de>
Cc:	John Youn <johnyoun@...opsys.com>, Felipe Balbi <balbi@...nel.org>,
	Heiko Stuebner <heiko@...ech.de>,
	Caesar Wang <caesar.upstream@...il.com>,
	Tao Huang <huangtao@...k-chips.com>,
	Remi Pommarel <repk@...plefau.lt>,
	Stefan Wahren <stefan.wahren@...e.com>,
	Julius Werner <jwerner@...omium.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFT PATCH 1/2] usb: dwc2: Add a 10 ms delay to dwc2_core_reset()

Hi,

On Fri, Mar 4, 2016 at 4:33 PM, Doug Anderson <dianders@...omium.org> wrote:
> Michael,
>
> On Fri, Mar 4, 2016 at 4:09 PM, Michael Niewoehner <linux@...ewoehner.de> wrote:
>>>> From testing and trying to make sense of the documentation, it appears
>>>> that a 10 ms delay is needed after resetting the core to make sure that
>>>> everything is stable and consistent.  Let's add it.
>>>>
>>>> In my testing (on rk3288) this allows us to revert commit
>>>> 192cb07f7928 ("usb: dwc2: Fix probe problem on bcm2835").  Though I
>>>> could never reproduce the problems on my board, this might also allow us
>>>> to revert commit bd84f4ae9986 ("usb: dwc2: Add extra delay when forcing
>>>> dr_mode").
>>>>
>>>> Signed-off-by: Douglas Anderson <dianders@...omium.org>
>>>
>>> Tested-by: Michael Niewoehner <linux@...ewoehner.de>
>
> Thanks!  That's great news!
>
>
>>> I’m a bit confused since git log says bd84f4ae9986 has been merged in 62718e304aa6 but looking at drivers/usb/dwc2/core.c it seems the patch has not been applied anyways ...
>>> However, I tested you your two patches with „magically reverted“ bd84f4ae9986 (msleep 50) on rk3188.
>>> The sdcard keeps being detected and boots just fine.
>> I meant usb stick of course… too much sdcards in my head today \o/.
>
> Odd.  It looks to be there for me...
>
> $ git checkout 62718e304aa6
> HEAD is now at 62718e304aa6... Merge tag 'usb-4.5-rc6' of
> git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb
>
> $ git grep -C3 "NOTE: This is required" -- drivers/usb/dwc2/core.c
> drivers/usb/dwc2/core.c-        }
> drivers/usb/dwc2/core.c-
> drivers/usb/dwc2/core.c-        /*
> drivers/usb/dwc2/core.c:         * NOTE: This is required for some
> rockchip soc based
> drivers/usb/dwc2/core.c-         * platforms.
> drivers/usb/dwc2/core.c-         */
> drivers/usb/dwc2/core.c-        msleep(50);

For anyone playing along at home, please see
<http://article.gmane.org/gmane.linux.usb.general/138355>.

-Doug