[RFC 1/1] usb: chipidea: ci_hdrc_imx: disable runtime pm for HSIC interface

[Alexander Stein]

With the add of power-domain support in commit 02f8eb40ef7b ("ARM: dts:
imx7s: Add power domain for imx7d HSIC") runtime suspend will disable
the power-domain. This prevents IRQs to occur when a new device is attached
on a downstream hub.

Signed-off-by: Alexander Stein <alexander.stein at ew.tq-group.com>
---
Our board TQMa7x + MBa7x (i.MX7 based) uses a HSIC link to mounted USB HUB on
usbh device. Cold plugging an USB mass storage device is working fine. But
once the last non-HUB device is disconnected the ci_hdrc device goes into
runtime suspend. This will eventually also disable the 'pgc_hsic_phy' power
domain. Results is that no more updates from USB hub is handled, neither HUB
on HSIC link or HUB on that's downstream link. USB tree looks like this:

/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ci_hdrc/1p, 480M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/4p, 480M
        |__ Port 1: Dev 3, If 0, Class=Hub, Driver=hub/4p, 480M
            |__ Port 1: Dev 4, If 0, Class=Mass Storage, Driver=usb-storage, 480M
        |__ Port 2: Dev 5, If 0, Class=Mass Storage, Driver=usb-storage, 480M

I noticed once the power domain is disabled, no IRQs appear if I attach a new
mass storage, essentially preventing any runtime resume.
I do not know if this is specific to i.MX7 only or if this is a general USB
HSIC problem, so this diff might be too much.

BTW: An udev rule with the same effect is:
ACTION=="add", SUBSYSTEMS=="platform", DRIVER=="ci_hdrc",
KERNELS=="30b30000.usb", TEST=="power/control", ATTR{power/control}="on"

But I would like to get this fixed on driver level.

Regards
Alexander

 drivers/usb/chipidea/ci_hdrc_imx.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/chipidea/ci_hdrc_imx.c b/drivers/usb/chipidea/ci_hdrc_imx.c
index 097142ffb184..e5c22b70431c 100644
--- a/drivers/usb/chipidea/ci_hdrc_imx.c
+++ b/drivers/usb/chipidea/ci_hdrc_imx.c
@@ -344,6 +344,8 @@ static int ci_hdrc_imx_probe(struct platform_device *pdev)
 	if ((of_usb_get_phy_mode(dev->of_node) == USBPHY_INTERFACE_MODE_HSIC)
 		&& data->usbmisc_data) {
 		pdata.flags |= CI_HDRC_IMX_IS_HSIC;
+		/* Runtime suspend is not supported for HSIC interface */
+		pdata.flags &= ~CI_HDRC_SUPPORTS_RUNTIME_PM;
 		data->usbmisc_data->hsic = 1;
 		data->pinctrl = devm_pinctrl_get(dev);
 		if (PTR_ERR(data->pinctrl) == -ENODEV)
-- 
2.25.1