linux-kernel - Re: [PATCH 2/4] usb: dwc3: Fix gadget pullup in SS mode

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Message-ID: <20120919160450.GA7510@arwen.pp.htv.fi>
Date:	Wed, 19 Sep 2012 19:04:51 +0300
From:	Felipe Balbi <balbi@...com>
To:	"Sonasath, Moiz" <m-sonasath@...com>
Cc:	balbi@...com, Kishon Vijay Abraham I <kishon@...com>,
	grant.likely@...retlab.ca, rob.herring@...xeda.com,
	rob@...dley.net, linux@....linux.org.uk, linux-usb@...r.kernel.org,
	linux-omap@...r.kernel.org, devicetree-discuss@...ts.ozlabs.org,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/4] usb: dwc3: Fix gadget pullup in SS mode

Hi,

On Wed, Sep 19, 2012 at 10:02:48AM -0500, Sonasath, Moiz wrote:
> Felipe,
> 
> On Wed, Sep 19, 2012 at 6:53 AM, Felipe Balbi <balbi@...com> wrote:
> 
> > Hi,
> >
> > On Wed, Sep 19, 2012 at 05:00:27PM +0530, Kishon Vijay Abraham I wrote:
> > > From: Moiz Sonasath <m-sonasath@...com>
> > >
> > > For the gadget pullup functionality to work in
> > > SS mode it requires a particular sequence of
> > > toggling the run-stop bit. Here is the required
> > > sequence:
> > >
> > > - Set DCTL[31]
> > > - Clear DCTL[31]
> > > - Clear OMAP5430_CONTROL_CORE__PHY_POWER_USB[14]
> > > - Clear DCTL[8:5] = 0x00
> > > - Set DCTL[8:5] = 0x05
> > > - Wait 25 Ms
> > > - Set DCTL[31]
> > > - Set OMAP5430_CONTROL_CORE__PHY_POWER_USB[14]
> > >
> > > Tested rigourously the gadget pull-up functionality
> > > in bot HS and SS modes.
> > >
> > > Signed-off-by: Moiz Sonasath <m-sonasath@...com>
> > > Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
> >
> > this needs to split into three patches:
> >
> > add new poweron field, implement it on omap-usb3, use it on
> > dwc3/gadget.c
> >
> > btw, I don't think the changes to run_stop bit are necessary and if they
> > are, that'd either be a silicon errata or it would've been mentioned on
> > the databook. I don't remember seeing that on the databook so I'm
> > assuming that this is caused by a bad use of the PHY.
> >
> > Why that mdelay(25) ? why 25 ms ? That's quite a long time, actually.
> >
> 
> Felipe, This is infact a HW bug that the Si-Val team did accept and gave us
> this workaround sequence with the precise delay :-)
> 
> Supposedly this will be fixed in ES 2.0.

in that case this doesn't have to go to mainline since we're not
supporting ES1.0 in mainline :-)

at minimum this should've come with a proper revision check anyway.

-- 
balbi

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