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usb: dwc3: of-simple: reset host controller at suspend/resume

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If we power off the SoC logic rail in S3, we can find that the Type-C
PHY can't initialize correctly after system resume. We need to toggle
the USB3-OTG reset before trying to initialize the PHY, or else it
times out.

    phy phy-ff800000.phy.9: phy poweron failed --> -110
    dwc3 fe900000.dwc3: failed to initialize core
    dwc3: probe of fe900000.dwc3 failed with error -110

Note that the RK3399 TRM suggests that we should keep the whole usb3
controller in reset for the duration of the Type-C PHY initialization.
However, it's hard to assert the reset in the current framework of
reset. We're still skeptical about that, and we haven't yet found a
case where this seems to have mattered. This approach is much easier, it
simply holds the USB3-OTG reset while device is supended.

The dwc3 core is going to reinitialize the controller at suspend/resume
anyway (including a "soft reset"), so it should be safe to do this.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
This commit is contained in:
Enric Balletbo i Serra 2018-07-16 12:25:47 +02:00 committed by Felipe Balbi
parent 1fcba97e35
commit 76251db865
1 changed files with 29 additions and 0 deletions
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29
drivers/usb/dwc3/dwc3-of-simple.c
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@ -28,6 +28,7 @@ struct dwc3_of_simple {
int num_clocks;
struct reset_control *resets;
bool pulse_resets;
bool need_reset;
};
static int dwc3_of_simple_clk_init(struct dwc3_of_simple *simple, int count)
@ -93,6 +94,13 @@ static int dwc3_of_simple_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, simple);
simple->dev = dev;
/*
* Some controllers need to toggle the usb3-otg reset before trying to
* initialize the PHY, otherwise the PHY times out.
*/
if (of_device_is_compatible(np, "rockchip,rk3399-dwc3"))
simple->need_reset = true;
if (of_device_is_compatible(np, "amlogic,meson-axg-dwc3") ||
of_device_is_compatible(np, "amlogic,meson-gxl-dwc3")) {
shared_resets = true;
@ -201,9 +209,30 @@ static int dwc3_of_simple_runtime_resume(struct device *dev)
return 0;
}
static int dwc3_of_simple_suspend(struct device *dev)
{
struct dwc3_of_simple *simple = dev_get_drvdata(dev);
if (simple->need_reset)
reset_control_assert(simple->resets);
return 0;
}
static int dwc3_of_simple_resume(struct device *dev)
{
struct dwc3_of_simple *simple = dev_get_drvdata(dev);
if (simple->need_reset)
reset_control_deassert(simple->resets);
return 0;
}
#endif
static const struct dev_pm_ops dwc3_of_simple_dev_pm_ops = {
SET_SYSTEM_SLEEP_PM_OPS(dwc3_of_simple_suspend, dwc3_of_simple_resume)
SET_RUNTIME_PM_OPS(dwc3_of_simple_runtime_suspend,
dwc3_of_simple_runtime_resume, NULL)
};