Hello all,
I am debugging some unexpected USB behavior on a i.MX6ULL SOC,
chipidea controller ("fsl,imx6ul-usb") and a fsl mxs usbphy
("fsl,imx6ul-usbphy").
The HW design has 2 USB interface, the first one is dual-role, while the second
one is a host port with NO way to re-read the VBUS (USB_OTG2_VBUS is not
really connected, there is just a capacitor to GND).
Focusing on the second interface, USB Host only, what I do experience is the
following:
- if there is no USB HUB connected and no device connected at boot, any USB
device hotplugged is not working, ci_runtime_suspend is called and it never
resume.
- if there is a HUB in between it somehow works, however I have a continuos
runtime powermanagement reset loop every 2 seconds
[ 1026.146360] ci_hdrc ci_hdrc.1: at ci_runtime_suspend
[ 1026.164725] ci_hdrc ci_hdrc.1: at ci_controller_resume
[ 1026.487844] usb 1-1: reset high-speed USB device number 2 using ci_hdrc
[ 1028.326789] ci_hdrc ci_hdrc.1: at ci_runtime_suspend
[ 1028.335378] ci_hdrc ci_hdrc.1: at ci_controller_resume
[ 1028.657853] usb 1-1: reset high-speed USB device number 2 using ci_hdrc
I was able to have it fully working disabling the runtime power management in
the chipidea driver or using sysfs (`echo on > /sys/.../power/control`).
--- a/drivers/usb/chipidea/ci_hdrc_imx.c
+++ b/drivers/usb/chipidea/ci_hdrc_imx.c
@@ -56,7 +56,7 @@ static const struct ci_hdrc_imx_platform_flag imx6sx_usb_data = {
};
static const struct ci_hdrc_imx_platform_flag imx6ul_usb_data = {
- .flags = CI_HDRC_SUPPORTS_RUNTIME_PM |
+ .flags =
I was digging even more into the topic and I found out that what is happening
is that mxs_phy_disconnect_line() is called. I than tried to remove the MXS_PHY_DISCONNECT_LINE_WITHOUT_VBUS flag.
--- a/drivers/usb/phy/phy-mxs-usb.c
+++ b/drivers/usb/phy/phy-mxs-usb.c
@@ -178,7 +178,7 @@ 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,
+ /*.flags = MXS_PHY_DISCONNECT_LINE_WITHOUT_VBUS,*/
};
This commit from NXP downstream kernel seems somehow related
https://github.com/nxp-imx/linux-imx/commit/89ec73836a9b1347743e406d62dd446dc4365db3
however it builds on other commits that allow to communicate the actual mode to
the USB PHY driver and prevent mxs_phy_disconnect_line() to be called for the
USB host case.
With that the situation is way better, but while without
`CI_HDRC_SUPPORTS_RUNTIME_PM` it works perfectly, without
`MXS_PHY_DISCONNECT_LINE_WITHOUT_VBUS` it does not really work smootly
in case there is a hub in between (~20% of the time the device is not
enumerated after plugging it in).
When it does not work I see that after plugging in a device runtime resume
function is called, but after that the device is not enumerated on the USB bus.
It looks like something else is missing.
It seems like having a pure USB Host interface without having a way to re-read
the VBUS is not really supported in SW at the moment, am I wrong?
Any idea?
One last comment, even the USB dual role port is not working smoothly, however
I have not investigated this specific case that much because disabling runtime pm
solves everything also in that case.
Francesco
