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: Tue, 27 Jan 2015 09:38:01 -0800 [thread overview]
Message-ID: <20150127173801.GA8441@psi-dev26.jf.intel.com> (raw)
In-Reply-To: <20150127092856.GD28539@kuha.fi.intel.com>
On Tue, Jan 27, 2015 at 11:28:56AM +0200, Heikki Krogerus wrote:
> On Mon, Jan 26, 2015 at 11:23:37AM -0800, David Cohen wrote:
> > On Mon, Jan 26, 2015 at 02:55:03PM +0200, Heikki Krogerus wrote:
> > > 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
>
> And if you look at dwc3_probe, you'll notice that it calls
> phy_power_on after that, and ulpi will most definitely be accessible
> at that point.
>
> I'm only using the init and exit hooks instead of just
> power_on/power_off because I'm not sure which the controllers will
> use. For example, now dwc3 calls phy_init() in it's resume routine and
> not phy_power_on() like I would expect. I know the problem has been
> pointed out by others, so I'm expecting we'll get guidelines for it
> later. But before we do, I see no harm in having both init and
> power_on hooks in this driver.
It sounds hackish to me. You could clearly change the logic on
init/power_on callbacks to avoid this problem.
>
> > During tusb1210 phy init from dwc3, you shouldn't access ulpi bus.
>
> We will end up executing one failed write followed by write that we
> know will succeed. Ideally we didn't have to do the first one at all,
> but I don't see any risk here.
Ditto.
>
> > > > > + 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
>
> The only reason why that board doesn't work is because of very much
> Baytrail-CR specific problems. These are are two issues, but the first
That's not BYT-CR specific problems. That's just dwc3 and tusb1210
interacting as they're expecting to.
> one is critical for getting it working. Both will be handled, but
> separately from this set:
>
> 1) The firmware leaves the PHY in reset, forcing us to enable it
> somehow in OS before accessing ulpi. Unless we can get a firmware fix
> for that (it's starting to look like it's not going to happen; please
> correct me if you know something else!), we need to add a quirk for
> Baytrails (attached), which is probable still OK. But IMO this really
> should be fixed in the firmware.
It seems you're expecting the PHY to be fully operational in order to
probe it. That's wrong assumption. BYT-CR's BIOS is doing nothing wrong
by leaving PHY on reset state. The real problem is what I stated above.
With your current logic, you'll get stuck with checking/egg problem: you
need phy probed to probe dwc3, but need dwc3 probed to power on phy.
You need a logic to break this circular dependency.
>
> 2) Since the gpio resources are given to the controller device in ACPI
> tables and there isn't separate device object for the PHY at all, we
> need to deliver the gpios somehow separately to the phy driver. There
> is a thread where we are talking about how to do that:
> https://lkml.org/lkml/2014/12/18/82
How about just leave the logic the way it is:
dwc3-pci.c registers platform_device with gpio as resource if the GPIOs
are provided to dwc3. If not, then dwc3-pci.c will expect phy to have
its own ACPI id.
Br, David
>
>
> Thanks,
>
> --
> heikki
> diff --git a/drivers/usb/dwc3/dwc3-pci.c b/drivers/usb/dwc3/dwc3-pci.c
> index 8d95056..53902ea 100644
> --- a/drivers/usb/dwc3/dwc3-pci.c
> +++ b/drivers/usb/dwc3/dwc3-pci.c
> @@ -21,6 +21,7 @@
> #include <linux/slab.h>
> #include <linux/pci.h>
> #include <linux/platform_device.h>
> +#include <linux/gpio/consumer.h>
>
> #include "platform_data.h"
>
> @@ -35,6 +36,24 @@
>
> static int dwc3_pci_quirks(struct pci_dev *pdev)
> {
> + if (pdev->vendor == PCI_VENDOR_ID_INTEL &&
> + pdev->device == PCI_DEVICE_ID_INTEL_BYT) {
> + struct gpio_desc *gpio;
> +
> + gpio = gpiod_get_index(&pdev->dev, "reset", 0);
> + if (!IS_ERR(gpio)) {
> + gpiod_direction_output(gpio, 0);
> + gpiod_set_value_cansleep(gpio, 1);
> + gpiod_put(gpio);
> + }
> + gpio = gpiod_get_index(&pdev->dev, "cs", 1);
> + if (!IS_ERR(gpio)) {
> + gpiod_direction_output(gpio, 0);
> + gpiod_set_value_cansleep(gpio, 1);
> + gpiod_put(gpio);
> + }
> + }
> +
> if (pdev->vendor == PCI_VENDOR_ID_AMD &&
> pdev->device == PCI_DEVICE_ID_AMD_NL_USB) {
> struct dwc3_platform_data pdata;
next prev parent reply other threads:[~2015-01-27 17:36 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
2015-01-27 9:28 ` Heikki Krogerus
2015-01-27 12:57 ` Heikki Krogerus
2015-01-27 17:38 ` David Cohen [this message]
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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