linux-kernel - Re: [PATCH 3/3] usb: dwc3: add a quirk for device disconnection issue in Synopsis dwc3 core

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Date:	Mon, 29 Dec 2014 10:06:41 -0600
From:	Felipe Balbi <balbi@...com>
To:	Sneeker Yeh <sneeker.yeh@...il.com>
CC:	Felipe Balbi <balbi@...com>, Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Mathias Nyman <mathias.nyman@...el.com>,
	Grant Likely <grant.likely@...aro.org>,
	Alan Stern <stern@...land.harvard.edu>,
	Arnd Bergmann <arnd@...db.de>, Paul Bolle <pebolle@...cali.nl>,
	Hans de Goede <hdegoede@...hat.com>,
	Thomas Pugliese <thomas.pugliese@...il.com>,
	David Mosberger <davidm@...uge.net>,
	Peter Griffin <peter.griffin@...aro.org>,
	Sylwester Nawrocki <s.nawrocki@...sung.com>,
	Andrew Bresticker <abrestic@...omium.org>,
	Gregory CLEMENT <gregory.clement@...e-electrons.com>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-usb@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	Andy Green <andy.green@...aro.org>,
	Jassi Brar <jaswinder.singh@...aro.org>,
	Sneeker Yeh <Sneeker.Yeh@...fujitsu.com>
Subject: Re: [PATCH 3/3] usb: dwc3: add a quirk for device disconnection
 issue in Synopsis dwc3 core

Hi,

On Mon, Dec 29, 2014 at 04:07:50PM +0800, Sneeker Yeh wrote:
> Hi,
> 
> 2014-12-29 14:41 GMT+08:00 Sneeker Yeh <sneeker.yeh@...il.com>:
> 
> > Hi,
> >
> > 2014-12-22 23:37 GMT+08:00 Felipe Balbi <balbi@...com>:
> >
> >> On Tue, Dec 16, 2014 at 10:10:28AM +0800, Sneeker Yeh wrote:
> >> > Synopsis DesignWare USB3 IP Core integrated with a config-free
> >> > phy needs special handling during device disconnection to avoid
> >> > the host controller dying.
> >> >
> >> > This quirk makes sure PORT_CSC is cleared after the disable slot
> >> > command when usb device is disconnected from internal root hub,
> >> > otherwise, Synopsis core would fall into a state that cannot use
> >> > any endpoint command. Consequently, device disconnection procedure
> >> > might not be finished because sometimes endpoint need to be stop
> >> > by endpoint stop command issuing.
> >> >
> >> > Symptom usually happens when disconnected device is keyboard,
> >> > mouse, and hub.
> >>
> >> you need to point us to the synopsys STARS ticket number. That's the
> >> only way to reference this specific quirk. Add it to a comment
> >> somewhere.
> >>
> >
> > Thanks, we're still waiting for Synopsis STARS ticket number.
> > I'll add it to comment later.
> >
> >
> Sorry I didn't express myself clearly.
> 
> So far Fujitsu Semiconductor got Synopsys internal case id , that is "
> Case: 8000679552".
> However the contents belongs this id cannot be referred except Fujitsu
> Semiconductor and Synopsys.
> Synopsis decide the official errata (STAR information) will be disclosed
> next February.
> 
> Would you suggest if this quirk can be accepted with this case ID, or can
> only be accepted with STARS ticket number?

The thing is that without the STARS number I can't really verify which
versions of the IP would be affected. Clearly, it's not only your setup
and I think it's pretty unfair to have "is_compatible("fujitsu")" to
enable the quirk only for you. Isn't there a better way of enabling the
quirk based off of revision detection couple with a look on GHWPARAMS*
registers ?

What's tricking me is this claim that only config-free PHYs would be
affected, why ?

I still have many questions about this patch which are not answered by
commit log nor can I poke around on Synopsys solvnet for answers :-s

-- 
balbi

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