From: Heikki Krogerus <heikki.krogerus@linux.intel.com>
To: David Cohen <david.a.cohen@linux.intel.com>
Cc: Felipe Balbi <balbi@ti.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Baolu Lu <baolu.lu@linux.intel.com>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 6/8] usb: dwc3: add ULPI interface support
Date: Fri, 13 Feb 2015 15:16:40 +0200 [thread overview]
Message-ID: <20150213131640.GC27695@kuha.fi.intel.com> (raw)
In-Reply-To: <20150213014130.GC21337@psi-dev26.jf.intel.com>
On Thu, Feb 12, 2015 at 05:41:30PM -0800, David Cohen wrote:
> On Thu, Feb 12, 2015 at 02:12:14PM +0200, Heikki Krogerus wrote:
> > > > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> > > > index a8c9062..66cbf38 100644
> > > > --- a/drivers/usb/dwc3/core.c
> > > > +++ b/drivers/usb/dwc3/core.c
> > > > @@ -879,6 +879,10 @@ static int dwc3_probe(struct platform_device *pdev)
> > > > platform_set_drvdata(pdev, dwc);
> > > > dwc3_cache_hwparams(dwc);
> > > >
> > > > + ret = dwc3_ulpi_init(dwc);
> > >
> > > If I understood correctly, this call will result in enumerating the phy
> > > via ULPI bus, then registering the correct ULPI device.
> > > Can you guarantee ULPI will be always accessible at this point if we
> > > remove dwc3 module and load it again?
> >
> > OK, got it. So yes, I can guarantee that ULPI will be acessible at
> > this point. If we are in a state where we could soft reset dwc3, we
> > know we can access ULPI. The fact that dwc3 itself expects to be able
> > to write to the ULPI registers at that point guarantees it for us.
>
> I just double checked DWC3 TRM.
> You are correct, by the time we're executing dwc3_core_soft_reset() ULPI
> bus is already accessible. But the TRM also specifies an ULPI phy would
> be reset by DCTL's core soft reset, which is executed by dwc3_core_init()
> before calling dwc3_core_soft_reset(). It does mention DWC3 writes data
> to an ULPI phy register during reset, but it also mentions the clock
> sync happens during that time.
>
> That makes no even OK, but more correct IMO to power on phy before
> core's soft reset (i.e. by ACPI methods). But it lets us in a grey area
> whether ULPI is reliably accessible before core's soft reset.
>
> I believe if you move the dwc3_ulpi_init() to dwc3_core_init(), after
> core's soft reset we've got no more grey area.
Well, we have already requested the phys in dwc3_probe before that so
some refactoring will be needed. It's probable no a problem.
Btw, I'm sorry about telling this so late, but I'm going to be on
vacation for the next two weeks.
Cheers,
--
heikki
next prev parent reply other threads:[~2015-02-13 13:16 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-23 15:12 [PATCH 0/8] usb: ulpi bus Heikki Krogerus
2015-01-23 15:12 ` [PATCH 1/8] usb: add bus type for USB ULPI Heikki Krogerus
2015-01-29 5:02 ` Felipe Balbi
2015-01-29 14:18 ` Heikki Krogerus
2015-02-13 1:44 ` Stephen Boyd
2015-02-13 11:24 ` Heikki Krogerus
2015-01-23 15:12 ` [PATCH 2/8] usb: dwc3: USB2 PHY register access bits Heikki Krogerus
2015-01-23 15:12 ` [PATCH 3/8] usb: dwc3: store driver data earlier Heikki Krogerus
2015-01-23 15:12 ` [PATCH 4/8] usb: dwc3: cache hwparams earlier Heikki Krogerus
2015-01-23 15:12 ` [PATCH 5/8] usb: dwc3: ULPI or UTMI+ select Heikki Krogerus
2015-01-23 15:12 ` [PATCH 6/8] usb: dwc3: add ULPI interface support Heikki Krogerus
2015-01-23 16:24 ` Felipe Balbi
2015-01-26 11:46 ` Heikki Krogerus
2015-01-26 19:35 ` Felipe Balbi
2015-01-27 11:09 ` Heikki Krogerus
2015-01-27 15:24 ` Felipe Balbi
2015-02-11 19:34 ` David Cohen
2015-02-12 12:12 ` Heikki Krogerus
2015-02-13 1:41 ` David Cohen
2015-02-13 1:54 ` David Cohen
2015-02-13 13:16 ` Heikki Krogerus [this message]
2015-02-13 22:03 ` David Cohen
2015-02-13 22:04 ` Felipe Balbi
2015-01-23 15:12 ` [PATCH 7/8] phy: helpers for USB ULPI PHY registering Heikki Krogerus
2015-01-29 5:03 ` Felipe Balbi
2015-01-29 14:34 ` Heikki Krogerus
2015-01-29 16:11 ` Felipe Balbi
2015-01-30 10:33 ` Heikki Krogerus
2015-01-30 16:03 ` Felipe Balbi
2015-01-23 15:12 ` [PATCH 8/8] phy: add driver for TI TUSB1210 ULPI PHY Heikki Krogerus
2015-01-24 23:58 ` David Cohen
2015-01-26 12:55 ` Heikki Krogerus
2015-01-26 19:23 ` David Cohen
2015-01-27 9:28 ` Heikki Krogerus
2015-01-27 12:57 ` Heikki Krogerus
2015-01-27 17:38 ` David Cohen
2015-01-28 14:20 ` Heikki Krogerus
2015-01-28 18:02 ` David Cohen
2015-01-29 14:14 ` Heikki Krogerus
2015-01-29 16:20 ` Felipe Balbi
2015-01-29 18:02 ` David Cohen
2015-01-30 12:18 ` Heikki Krogerus
2015-01-30 16:09 ` David Cohen
2015-02-02 12:50 ` Heikki Krogerus
2015-01-30 9:29 ` Heikki Krogerus
2015-01-30 16:14 ` Felipe Balbi
2015-01-30 16:25 ` David Cohen
2015-01-30 16:30 ` Felipe Balbi
2015-01-30 16:20 ` David Cohen
2015-01-30 16:33 ` Felipe Balbi
2015-02-02 12:59 ` Heikki Krogerus
2015-02-03 11:37 ` Heikki Krogerus
2015-02-10 18:33 ` David Cohen
2015-02-10 19:05 ` David Cohen
2015-02-10 19:23 ` David Cohen
2015-02-11 13:12 ` Heikki Krogerus
2015-02-11 19:36 ` David Cohen
2015-02-13 22:02 ` David Cohen
2015-02-13 22:03 ` Felipe Balbi
2015-02-13 22:13 ` David Cohen
2015-01-29 5:09 ` Felipe Balbi
2015-01-29 14:30 ` Heikki Krogerus
2015-01-29 16:20 ` Felipe Balbi
2015-01-29 18:04 ` David Cohen
2015-01-29 18:25 ` David Cohen
2015-01-29 18:47 ` David Cohen
2015-01-30 10:30 ` Heikki Krogerus
2015-02-13 1:52 ` David Cohen
2015-02-13 12:35 ` Heikki Krogerus
2015-02-13 16:01 ` Felipe Balbi
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