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

Francesco Dolcini
2023-05-04T16:50:49Z

Hello Luca,
I guess your mail to Philippe bounced, let me try to answer since I am aware
of the issue here.

On Thu, May 04, 2023 at 06:23:12PM +0200, Luca Ceresoli wrote:
> I found this thread after several hours spent in debugging why USB host is
> not detecting new devices on a custom board using the iMX6ULL Colibri
> SoM.
>
> My best workaround at the moment is:
We have the same workaround in our BSP since quite some time, see
https://git.toradex.com/cgit/meta-toradex-bsp-common.git/tree/recipes-kernel/linux/linux-toradex-mainline-git/0002-drivers-chipidea-disable-runtime-pm-for-imx6ul.patch

> I haven't found any follow-up patches from you, so I'm wondering whether
> you have made any progress on this issue.
You can find the latest discussion on that regard here
https://lore.kernel.org/all/Y1vLpaxpc5WBCuGD@francesco-nb.int.toradex.com/

> As I see it, a quirk in the driver would make sense.
I am not sure.

The reason this is not working is that the VBUS is not directly
connected to the SOC and the USB IP is powered in a different way (all
of that was reviewed/acked by NXP when the board was designed).

The issue is in drivers/usb/phy/phy-mxs-usb.c:mxs_phy_disconnect_line(),
however:
1 - checking for the VBUS when in host mode is not correct.
2 - checking for the VBUS when in OTG/dual-role mode should be done using
extcon or equivalent. In this case on the colibri-imx6ull you would get
the correct behavior.

The NXP downstream kernel has some improvements on that regard, for
instance 1 would work, 2 I am not 100% sure.

Here the related patches:

From 60422d8301fc354e69ec0184831468c3b65cc26a Mon Sep 17 00:00:00 2001
From: Li Jun <jun.li@nxp.com>
Date: Wed, 12 Apr 2017 05:31:17 +0800
Subject: [PATCH 1/3] MLK-14285-1 usb: phy: add usb mode for usb_phy

USB phy driver may need to know the current working mode of
the controller, and does some different settings according to
host mode or device mode.

Signed-off-by: Li Jun <jun.li@nxp.com>
(cherry picked from commit 2286cb30feedd6f4a5cb82a0f0af5aa3a04ab698)
Signed-off-by: Vipul Kumar <vipul_kumar@mentor.com>
Signed-off-by: Srikanth Krishnakar <Srikanth_Krishnakar@mentor.com>
---
include/linux/usb/phy.h | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)

diff --git a/include/linux/usb/phy.h b/include/linux/usb/phy.h
index e4de6bc1f69b..93963a018a13 100644
--- a/include/linux/usb/phy.h
+++ b/include/linux/usb/phy.h
@@ -63,6 +63,13 @@ enum usb_otg_state {
OTG_STATE_A_VBUS_ERR,
};

+/* The usb role of phy to be working with */
+enum usb_current_mode {
+ CUR_USB_MODE_NONE,
+ CUR_USB_MODE_HOST,
+ CUR_USB_MODE_DEVICE,
+};
+
struct usb_phy;
struct usb_otg;

@@ -155,6 +162,10 @@ struct usb_phy {
* manually detect the charger type.
*/
enum usb_charger_type (*charger_detect)(struct usb_phy *x);
+
+ int (*set_mode)(struct usb_phy *x,
+ enum usb_current_mode mode);
+
};

/* for board-specific init logic */
@@ -213,6 +224,15 @@ usb_phy_vbus_off(struct usb_phy *x)
return x->set_vbus(x, false);
}

+static inline int
+usb_phy_set_mode(struct usb_phy *x, enum usb_current_mode mode)
+{
+ if (!x || !x->set_mode)
+ return 0;
+
+ return x->set_mode(x, mode);
+}
+
/* for usb host and peripheral controller drivers */
#if IS_ENABLED(CONFIG_USB_PHY)
extern struct usb_phy *usb_get_phy(enum usb_phy_type type);

From cf3f741f4b7ab5d139938c4c0cd65d4547d386ff Mon Sep 17 00:00:00 2001
From: Li Jun <jun.li@nxp.com>
Date: Wed, 12 Apr 2017 05:41:21 +0800
Subject: [PATCH 2/3] MLK-14285-3 usb: phy: mxs: optimize disconnect line
condition

We only have below cases to disconnect line when suspend:
1. Device mode without connection to any host/charger(no vbus).
2. Device mode connect to a charger(w/ vbus), usb suspend when
system is entering suspend.
This patch can fix usb phy wrongly does disconnect line in case
some usb host enters suspend but vbus is off.

Signed-off-by: Li Jun <jun.li@nxp.com>
(cherry picked from commit 2af48913f77cec3658f5863b13f63619d8101279)
---
drivers/usb/phy/phy-mxs-usb.c | 32 ++++++++++++++++++--------------
1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/drivers/usb/phy/phy-mxs-usb.c b/drivers/usb/phy/phy-mxs-usb.c
index 8a262c5a0408..31f40dbb71c0 100644
--- a/drivers/usb/phy/phy-mxs-usb.c
+++ b/drivers/usb/phy/phy-mxs-usb.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0+
/*
- * Copyright 2012-2014 Freescale Semiconductor, Inc.
+ * Copyright 2012-2016 Freescale Semiconductor, Inc.
+ * Copyright 2017 NXP
* Copyright (C) 2012 Marek Vasut <marex@denx.de>
* on behalf of DENX Software Engineering GmbH
*/
@@ -204,6 +205,7 @@ struct mxs_phy {
int port_id;
u32 tx_reg_set;
u32 tx_reg_mask;
+ enum usb_current_mode mode;
};

static inline bool is_imx6q_phy(struct mxs_phy *mxs_phy)
@@ -386,18 +388,6 @@ static void __mxs_phy_disconnect_line(struct mxs_phy *mxs_phy, bool disconnect)
usleep_range(500, 1000);
}

-static bool mxs_phy_is_otg_host(struct mxs_phy *mxs_phy)
-{
- void __iomem *base = mxs_phy->phy.io_priv;
- u32 phyctrl = readl(base + HW_USBPHY_CTRL);
-
- if (IS_ENABLED(CONFIG_USB_OTG) &&
- !(phyctrl & BM_USBPHY_CTRL_OTG_ID_VALUE))
- return true;
-
- return false;
-}
-
static void mxs_phy_disconnect_line(struct mxs_phy *mxs_phy, bool on)
{
bool vbus_is_on = false;
@@ -412,7 +402,7 @@ static void mxs_phy_disconnect_line(struct mxs_phy *mxs_phy, bool on)

vbus_is_on = mxs_phy_get_vbus_status(mxs_phy);

- if (on && !vbus_is_on && !mxs_phy_is_otg_host(mxs_phy))
+ if (on && ((!vbus_is_on && mxs_phy->mode != CUR_USB_MODE_HOST)))
__mxs_phy_disconnect_line(mxs_phy, true);
else
__mxs_phy_disconnect_line(mxs_phy, false);
@@ -708,6 +698,19 @@ static enum usb_charger_type mxs_phy_charger_detect(struct usb_phy *phy)
return chgr_type;
}

+/*
+ * Set the usb current role for phy.
+ */
+static int mxs_phy_set_mode(struct usb_phy *phy,
+ enum usb_current_mode mode)
+{
+ struct mxs_phy *mxs_phy = to_mxs_phy(phy);
+
+ mxs_phy->mode = mode;
+
+ return 0;
+}
+
static int mxs_phy_probe(struct platform_device *pdev)
{
void __iomem *base;
@@ -793,6 +796,7 @@ static int mxs_phy_probe(struct platform_device *pdev)

mxs_phy->clk = clk;
mxs_phy->data = of_device_get_match_data(&pdev->dev);
+ mxs_phy->phy.set_mode = mxs_phy_set_mode;

platform_set_drvdata(pdev, mxs_phy);

From d4c4385b997f32b081e859d491f25f5beb738ae9 Mon Sep 17 00:00:00 2001
From: Li Jun <jun.li@nxp.com>
Date: Wed, 12 Apr 2017 05:38:48 +0800
Subject: [PATCH 3/3] MLK-14285-2 usb: chipidea: set mode for usb phy driver

After enters one specific role, notify usb phy driver.

Signed-off-by: Li Jun <jun.li@nxp.com>
(cherry picked from commit d3aa2a13f4e47bc7fae7f2eee1e86291d7513312)
---
drivers/usb/chipidea/ci.h | 21 ++++++++++++++++++---
1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/chipidea/ci.h b/drivers/usb/chipidea/ci.h
index 99440baa6458..9d7ba902246d 100644
--- a/drivers/usb/chipidea/ci.h
+++ b/drivers/usb/chipidea/ci.h
@@ -274,9 +274,21 @@ static inline int ci_role_start(struct ci_hdrc *ci, enum ci_role role)
return -ENXIO;

ret = ci->roles[role]->start(ci);
- if (!ret)
- ci->role = role;
- return ret;
+ if (ret)
+ return ret;
+
+ ci->role = role;
+
+ if (ci->usb_phy) {
+ if (role == CI_ROLE_HOST)
+ usb_phy_set_mode(ci->usb_phy,
+ CUR_USB_MODE_HOST);
+ else
+ usb_phy_set_mode(ci->usb_phy,
+ CUR_USB_MODE_DEVICE);
+ }
+
+ return 0;
}

static inline void ci_role_stop(struct ci_hdrc *ci)
@@ -289,6 +301,9 @@ static inline void ci_role_stop(struct ci_hdrc *ci)
ci->role = CI_ROLE_END;

ci->roles[role]->stop(ci);
+
+ if (ci->usb_phy)
+ usb_phy_set_mode(ci->usb_phy, CUR_USB_MODE_NONE);
}

static inline enum usb_role ci_role_to_usb_role(struct ci_hdrc *ci)

Francesco