Date: Tue, 6 Jun 2017 09:55:28 +0800
From: Peter Chen <hzpeterchen@gmail.com>
To: Fabien Lahoudere <fabien.lahoudere@collabora.co.uk>
CC: Stephen Boyd <sboyd@codeaurora.org>, Peter Chen <peter.chen@nxp.com>,
        Peter Senna Tschudin <peter.senna@collabora.com>,
        Felipe Balbi <balbi@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "open list:USB PHY LAYER" <linux-usb@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] usb-phy-generic: Add support to SMSC USB3315
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On Mon, Jun 05, 2017 at 11:52:26AM +0200, Fabien Lahoudere wrote:
> On Mon, 2017-06-05 at 17:43 +0800, Peter Chen wrote:
> > On Mon, Jun 05, 2017 at 10:57:00AM +0200, Fabien Lahoudere wrote:
> > > On Fri, 2017-06-02 at 15:00 -0700, Stephen Boyd wrote:
> > > > On 05/26, Fabien Lahoudere wrote:
> > > > > Hello
> > > > > 
> > > > > I modify ci_hrdc_imx_probe to bypass?"data->phy = devm_usb_get_phy_by_phandle(&pdev->dev,
> > > > > "fsl,usbphy", 0);". Everything works as expected and call ci_ulpi_init.
> > > > > 
> > > > > The problem is that in ci_ulpi_init, before calling "ci->ulpi = ulpi_register_interface(ci-
> > > > > >dev,
> > > > > &ci->ulpi_ops);" (to initialize our phy), "hw_phymode_configure(ci);" is called which is the
> > > > > original function that make our system to hang.
> > > > > 
> > > > > Our phy is not initialised before calling ulpi_register_interface so I don't understand how
> > > > > the
> > > > > phy
> > > > > can reply if it is not out of reset state.
> > > > 
> > > > I haven't see any problem in hw_phymode_configure(). What's the
> > > > value of ci->platdata->phy_mode? USBPHY_INTERFACE_MODE_ULPI? If
> > > > you phy needs to be taken out of reset to reply to the ulpi reads
> > > > of the vendor/product ids, then it sounds like you have a similar
> > > > situation to what I had. I needed to turn on some regulators to
> > > > get those reads to work, otherwise they would fail, but knowing
> > > > what needed to be turned on basically meant I needed to probe the
> > > > ulpi driver so probing the ids wasn't going to be useful. So on
> > > > my device the reads for the ids go through, but they get all
> > > > zeroes back, which is actually ok because there aren't any bits
> > > > set on my devices anyway. After the reads see 0, we fallback to
> > > > DT matching, which avoids the "bring it out of reset/power it on"
> > > > sorts of problems entirely.
> > > > 
> > > 
> > > Yes the phy mode is configured to USBPHY_INTERFACE_MODE_ULPI.
> > > Indeed, this phy need to be out of reset to work. For example everything works fine if I call?
> > > "_ci_usb_phy_init(ci);" before calling "hw_phymode_configure(ci);"
> > > This function only init reset GPIO and clock.
> > > 
> > > For information, the original patch I have to fix the issue:
> > > 
> > > diff --git a/drivers/usb/chipidea/core.c b/drivers/usb/chipidea/core.c
> > > index 79ad8e9..21aaff1 100644
> > > --- a/drivers/usb/chipidea/core.c
> > > +++ b/drivers/usb/chipidea/core.c
> > > @@ -391,6 +391,7 @@ static int ci_usb_phy_init(struct ci_hdrc *ci)
> > > ?	case USBPHY_INTERFACE_MODE_UTMI:
> > > ?	case USBPHY_INTERFACE_MODE_UTMIW:
> > > ?	case USBPHY_INTERFACE_MODE_HSIC:
> > > +	case USBPHY_INTERFACE_MODE_ULPI:
> > > ?		ret = _ci_usb_phy_init(ci);
> > > ?		if (!ret)
> > > ?			hw_wait_phy_stable();
> > > @@ -398,7 +399,6 @@ static int ci_usb_phy_init(struct ci_hdrc *ci)
> > > ?			return ret;
> > > ?		hw_phymode_configure(ci);
> > > ?		break;
> > > -	case USBPHY_INTERFACE_MODE_ULPI:
> > > ?	case USBPHY_INTERFACE_MODE_SERIAL:
> > > ?		hw_phymode_configure(ci);
> > > ?		ret = _ci_usb_phy_init(ci);
> > > --?
> > 
> > Currently, the hw_phymode_configure is called twice for ULPI PHY, the
> > two execution are between _ci_usb_phy_init, would you test which one
> > causes hang? If the second causes hang, you can make a patch for
> > hw_phymode_configure that if the required PORTSC_PTS is the same
> > the value in register, do noop.
> 
> The first one hangs,?_ci_usb_phy_init is not called due to hang.
> 

So, you need to comment out hw_phymode_configure at ci_ulpi_init, and you
can't get vid/pid correctly, right? If it is, we may need to add power on
sequence at chipidea core driver (ci_hdrc_probe) for clock and reset things.

http://www.spinics.net/lists/linux-usb/msg157134.html

I am wondering if we can call ci_usb_phy_init before calling ci_ulpi_init,
since we need to let hardware be ready before reading vid/pid.
Stephen & Fabien, does that work for you?

-- 

Best Regards,
Peter Chen