From: David Cohen <david.a.cohen@linux.intel.com>
To: Heikki Krogerus <heikki.krogerus@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,
Kishon Vijay Abraham I <kishon@ti.com>
Subject: Re: [PATCH 8/8] phy: add driver for TI TUSB1210 ULPI PHY
Date: Mon, 26 Jan 2015 11:23:37 -0800 [thread overview]
Message-ID: <20150126192337.GA13936@psi-dev26.jf.intel.com> (raw)
In-Reply-To: <20150126125503.GB28539@kuha.fi.intel.com>
Hi Heikki,
On Mon, Jan 26, 2015 at 02:55:03PM +0200, Heikki Krogerus wrote:
> Hi David,
>
> On Sat, Jan 24, 2015 at 03:58:11PM -0800, David Cohen wrote:
> > > +static int tusb1210_power_on(struct phy *phy)
> > > +{
> > > + struct tusb1210 *tusb = phy_get_drvdata(phy);
> > > +
> > > + gpiod_set_value_cansleep(tusb->gpio_reset, 1);
> > > + gpiod_set_value_cansleep(tusb->gpio_cs, 1);
> > > +
> > > + /* Restore eye diagram optimisation value */
> > > + ulpi_write(tusb->ulpi, TUSB1210_VENDOR_SPECIFIC2,
> > > + tusb->eye_diagram_tuning);
> >
> > After you power on phy, ulpi bus may not be available right away. In
> > intel case, phy power on happens during dwc3 power on. ULPI bus is not
> > available until OTG controller and phy are in sync.
> >
> > In resume, you can't restore eye diagram from here.
>
> I'm sorry but I don't think I understand? Where do we power on the phy
> before dwc3 is powered on? Or is this a Baytrail-CR specific problem?
> I can't see any problems with the hardware I have.
You can't see in single accesses. But you may see when running stability
tests overnight.
Anyway, look for dwc3_core_soft_reset() function:
- dwc3 goes to reset state
- phy is initialized (or at least gets ready to sync clocks)
- dwc3 goes out or reset state
During tusb1210 phy init from dwc3, you shouldn't access ulpi bus.
>
> In any case, this sounds like purely dwc3 issue and not tusb1210
> issue.
That's neither purely dwc3's not tusb1210's, that's your problem :)
Since it's a potential bug introduced by your patch set here.
>
> > > +static int tusb1210_probe(struct ulpi *ulpi)
> > > +{
> > > + struct gpio_desc *gpio;
> > > + struct tusb1210 *tusb;
> > > + int ret;
> > > +
> > > + tusb = devm_kzalloc(&ulpi->dev, sizeof(*tusb), GFP_KERNEL);
> > > + if (!tusb)
> > > + return -ENOMEM;
> > > +
> > > + gpio = devm_gpiod_get(&ulpi->dev, "reset");
> > > + if (!IS_ERR(gpio)) {
> > > + ret = gpiod_direction_output(gpio, 0);
> > > + if (ret)
> > > + return ret;
> > > + tusb->gpio_reset = gpio;
> > > + }
> >
> > You cannot proceed with probe if gpio reset is not available. Different
> > from CS, it's a mandatory pin to toggle in order to power on/off phy and
> > get it in sync with OTG controller.
>
> Well, let's check -ENOENT and -ENODEV return values separately. The
> reset pin is not used on all platforms so getting this gpio is
> optional. This is the case even with some Intel's platforms using
> TUSB1210.
I doublechecked the tusb1210 datasheet. Despite the power on sequence
mentions RESET toggling as required, it has a comment later on that it
can be tied to VDDIO.
So as you mentioned, it'd be better to ignore -ENOENT and -ENODEV and
raise error otherwise.
>
> > > +
> > > + gpio = devm_gpiod_get(&ulpi->dev, "cs");
> > > + if (!IS_ERR(gpio)) {
> > > + ret = gpiod_direction_output(gpio, 0);
> > > + if (ret)
> > > + return ret;
> > > + tusb->gpio_cs = gpio;
> > > + }
> > > +
> > > + /* Store initial eye diagram optimisation value */
> > > + ret = ulpi_read(ulpi, TUSB1210_VENDOR_SPECIFIC2);
> >
> > It's unclear if ulpi is accessible at this point. You can't read it at
> > this point.
>
> We wouldn't have reached this point if ulpi wasn't accessible.
> Registering the ulpi interface would have already failed so no driver
> would have been probed.
You have a chicken/egg problem here:
- dwc3 needs phy to complete soft reset during probe
- tusb1210 needs dwc3 soft reset completed to be accessible via ULPI
Can you share how tusb1210 is connected on the platform you're using as
test for this patch? I don't think this driver would work reliably with
this device:
http://liliputing.com/2014/11/trekstor-launches-first-android-tablet-based-intels-irda-reference-design.html
Br, David
>
>
> Thanks!
>
> --
> heikki
next prev parent reply other threads:[~2015-01-26 19:22 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
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 [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20150126192337.GA13936@psi-dev26.jf.intel.com \
--to=david.a.cohen@linux.intel.com \
--cc=balbi@ti.com \
--cc=baolu.lu@linux.intel.com \
--cc=gregkh@linuxfoundation.org \
--cc=heikki.krogerus@linux.intel.com \
--cc=kishon@ti.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-usb@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).