Hi,
On 08-07-19 04:25, Chen, Hu wrote:
On some Broxton NUC, the usb role is lost after S3 (it becomes "none").
Add PM callbacks to address this issue: save the role during suspend and
restore usb to that role during resume.
Test:
Run Android on UC6CAY, a NUC powered by Broxton. Access this NUC via
"adb shell" from a host PC. After a suspend/resume cycle, the adb still
works well.
Signed-off-by: Chen, Hu <hu1.chen@xxxxxxxxx>
Signed-off-by: Balaji <m.balaji@xxxxxxxxx>
Hmm, but what if the user has say unplugged a host-adapter with a usb-stick
in there and plugged in a cable to a computer *while suspended* because the
battery was getting low?
I see 2 scenarios here:
1) We may get an interrupt for the role change, followed by an
intel_xhci_usb_set_role. In this case the interrupt handling may happen
before the intel_xhci_usb_resume call and we would end up restoring the
wrong value
2) The role may be changed underneath us by the firmware / AML code
without us ever becoming aware of this.
For the specific problem discussed in the commit message it might be better
to do something like:
static int intel_xhci_usb_resume(struct platform_device *pdev)
{
struct intel_xhci_usb_data *data = platform_get_drvdata(pdev);
struct device *dev = &pdev->dev;
if (intel_xhci_usb_get_role(dev) == USB_ROLE_NONE &&
power_supply_is_system_supplied())
intel_xhci_usb_set_role(dev, USB_ROLE_DEVICE);
return 0;
}
But that is somewhat specific for solving the problem described in
the commit message, but it has the advantage of not being able to
cause any regressions (that I can think of).
Regards,
Hans
diff --git a/drivers/usb/roles/intel-xhci-usb-role-switch.c b/drivers/usb/roles/intel-xhci-usb-role-switch.c
index 277de96181f9..caa1cfab41cc 100644
--- a/drivers/usb/roles/intel-xhci-usb-role-switch.c
+++ b/drivers/usb/roles/intel-xhci-usb-role-switch.c
@@ -37,6 +37,7 @@
struct intel_xhci_usb_data {
struct usb_role_switch *role_sw;
void __iomem *base;
+ enum usb_role role;
};
static int intel_xhci_usb_set_role(struct device *dev, enum usb_role role)
@@ -167,6 +168,30 @@ static int intel_xhci_usb_remove(struct platform_device *pdev)
return 0;
}
+static int intel_xhci_usb_suspend(struct platform_device *pdev,
+ pm_message_t state)
+{
+ struct intel_xhci_usb_data *data = platform_get_drvdata(pdev);
+ struct device *dev = &pdev->dev;
+
+ data->role = intel_xhci_usb_get_role(dev);
+
+ return 0;
+}
+
+static int intel_xhci_usb_resume(struct platform_device *pdev)
+{
+ struct intel_xhci_usb_data *data = platform_get_drvdata(pdev);
+ struct device *dev = &pdev->dev;
+
+ if (intel_xhci_usb_get_role(dev) != data->role) {
+ if (intel_xhci_usb_set_role(dev, data->role) != 0)
+ dev_warn(dev, "Failed to set role during resume\n");
+ }
+
+ return 0;
+}
+
static const struct platform_device_id intel_xhci_usb_table[] = {
{ .name = DRV_NAME },
{}
@@ -180,6 +205,8 @@ static struct platform_driver intel_xhci_usb_driver = {
.id_table = intel_xhci_usb_table,
.probe = intel_xhci_usb_probe,
.remove = intel_xhci_usb_remove,
+ .suspend = intel_xhci_usb_suspend,
+ .resume = intel_xhci_usb_resume,
};
module_platform_driver(intel_xhci_usb_driver);
