linux-kernel - Re: [EXT] Re: [PATCH v2 2/3] usb: chipidea: imx: support disabling runtime-pm

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Message-ID: <20230719184831.75ae8658@booty>
Date:   Wed, 19 Jul 2023 18:48:31 +0200
From:   Luca Ceresoli <luca.ceresoli@...tlin.com>
To:     Xu Yang <xu.yang_2@....com>
Cc:     Francesco Dolcini <francesco@...cini.it>, Jun Li <jun.li@....com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "festevam@...il.com" <festevam@...il.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        dl-linux-imx <linux-imx@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Francesco Dolcini <francesco.dolcini@...adex.com>
Subject: Re: [EXT] Re: [PATCH v2 2/3] usb: chipidea: imx: support disabling
 runtime-pm

Hello Xu,

thanks for the follow up.

On Wed, 19 Jul 2023 11:23:26 +0000
Xu Yang <xu.yang_2@....com> wrote:

> Hi Luca,
> 
> > -----Original Message-----
> > 
> > Hello Xu,
> > 
> > On Tue, 18 Jul 2023 08:31:48 +0000
> > Xu Yang <xu.yang_2@....com> wrote:
> >   
> > > > -----Original Message-----
> > > >
> > > > Ciao Francesco,
> > > >
> > > > On Thu, 6 Jul 2023 12:23:43 +0200
> > > > Francesco Dolcini <francesco@...cini.it> wrote:
> > > >  
> > > > > Hello Luca,
> > > > >
> > > > > On Tue, May 30, 2023 at 11:22:51AM +0000, Jun Li wrote:  
> > > > > > Yes, your understanding is correct, talked with Xu(in CC), he will take this
> > > > > > soon.  
> > > > >
> > > > > A series was posted
> > > > >
> > > > > I had no time to try or look at it yet.  
> > > >
> > > > Thanks for keeping me up to date on this topic, which is still totally
> > > > relevant to me.
> > > >
> > > > I looked at the series, but it does not seem to be addressing the
> > > > problem with USB host not detecting new devices when VBUS is not
> > > > directly connected, e.g. in the Colibri imx6ull SoM.
> > > >
> > > > Xu, do you confirm the series at the link is _not_ solving the problem
> > > > being discussed here?  
> > >
> > > Have you tried this patchset? The upstream driver couldn't get correct
> > > USB role from HW_USBPHY_CTRL register when the ID pin is float. This is
> > > what this patchset is trying to fix. With this patch, condition
> > > "(!vbus_is_on && !mxs_phy_is_otg_host(mxs_phy)" will always be false when
> > > controller acts as host role, then __mxs_phy_disconnect_line(phy, true)
> > > will never be called. So I think it doesn't matter whether VBUS is connected
> > > or not when act as host mode. If you still have issue after apply this patchset,
> > > please let me know.  
> > 
> > I tested this patchset on top of v6.5-rc2 and I confirm USB detection
> > is still broken on the Colibri iMX6ULL. With or without the patches
> > the behavior is the same: USB devices are detected only during boot,
> > and anything connected after boot are never detected.  
> 
> Thanks for your feedback. As you said this issue will disappear with below change, right?
> 
> 	diff --git a/drivers/usb/phy/phy-mxs-usb.c b/drivers/usb/phy/phy-mxs-usb.c
> 	index e1a2b2ea098b..ec5ee790455e 100644
> 	--- a/drivers/usb/phy/phy-mxs-usb.c
> 	+++ b/drivers/usb/phy/phy-mxs-usb.c
> 	@@ -178,7 +178,6 @@ static const struct mxs_phy_data imx6sx_phy_data = {
> 	 };
> 
> 	 static const struct mxs_phy_data imx6ul_phy_data = {
> 	-       .flags = MXS_PHY_DISCONNECT_LINE_WITHOUT_VBUS,
> 	 };
> 
> 	 static const struct mxs_phy_data imx7ulp_phy_data = {

Exactly.

> So I guess something in __mxs_phy_disconnect_line(mxs_phy, true) is causing this behavior.
> Could you please help to find which line to comment to make this issue disappear?

I did some tests and detection works by doing _any_ of the following
two changes (or both of them).

Change 1:

--- a/drivers/usb/phy/phy-mxs-usb.c
+++ b/drivers/usb/phy/phy-mxs-usb.c
@@ -359,10 +359,6 @@ static void __mxs_phy_disconnect_line(struct mxs_phy *mxs_phy, bool disconnect)
        void __iomem *base = mxs_phy->phy.io_priv;
        u32 reg;
 
-       if (disconnect)
-               writel_relaxed(BM_USBPHY_DEBUG_CLKGATE,
-                       base + HW_USBPHY_DEBUG_CLR);
-
        if (mxs_phy->port_id == 0) {
                reg = disconnect ? ANADIG_USB1_LOOPBACK_SET
                        : ANADIG_USB1_LOOPBACK_CLR;

Change 2:

--- a/drivers/usb/phy/phy-mxs-usb.c
+++ b/drivers/usb/phy/phy-mxs-usb.c
@@ -372,9 +372,6 @@ static void __mxs_phy_disconnect_line(struct mxs_phy *mxs_phy, bool disconnect)
        } else if (mxs_phy->port_id == 1) {
                reg = disconnect ? ANADIG_USB2_LOOPBACK_SET
                        : ANADIG_USB2_LOOPBACK_CLR;
-               regmap_write(mxs_phy->regmap_anatop, reg,
-                       BM_ANADIG_USB2_LOOPBACK_UTMI_DIG_TST1 |
-                       BM_ANADIG_USB2_LOOPBACK_TSTI_TX_EN);
        }
 
        if (!disconnect)

I hope this clarifies something to you.

Luca

-- 
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com