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usb: dwc2: optionally assert phy reset when waking up

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On the rk3288 USB host-only port (the one that's not the OTG-enabled
port) the PHY can get into a bad state when a wakeup is asserted (not
just a wakeup from full system suspend but also a wakeup from
autosuspend).

We can get the PHY out of its bad state by asserting its "port reset",
but unfortunately that seems to assert a reset onto the USB bus so it
could confuse things if we don't actually deenumerate / reenumerate the
device.

We can also get the PHY out of its bad state by fully resetting it using
the reset from the CRU (clock reset unit), which does a more full
reset.  The CRU-based reset appears to actually cause devices on the bus
to be removed and reinserted, which fixes the problem (albeit in a hacky
way).

It's unfortunate that we need to do a full re-enumeration of devices at
wakeup time, but this is better than alternative of letting the bus get
wedged.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Yunzhi Li <lyz@rock-chips.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
This commit is contained in:
Douglas Anderson
2019-04-16 14:53:49 -07:00
committed by Felipe Balbi
parent cc389eaabd
commit c40cf7705e
4 changed files with 44 additions and 3 deletions
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9
drivers/usb/dwc2/platform.c
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@@ -481,6 +481,15 @@ static int dwc2_driver_probe(struct platform_device *dev)
hsotg->gadget_enabled = 1;
}
hsotg->reset_phy_on_wake =
of_property_read_bool(dev->dev.of_node,
"snps,reset-phy-on-wake");
if (hsotg->reset_phy_on_wake && !hsotg->phy) {
dev_warn(hsotg->dev,
"Quirk reset-phy-on-wake only supports generic PHYs\n");
hsotg->reset_phy_on_wake = false;
}
if (hsotg->dr_mode != USB_DR_MODE_PERIPHERAL) {
retval = dwc2_hcd_init(hsotg);
if (retval) {