[PATCH 2/2] usb: xhci-plat: add xhci-no-soft-retry-quirk device property

[Matt Eaton via B4 Relay]

From: Matt Eaton <linux@xxxxxxxxxxxxxx>

XHCI_NO_SOFT_RETRY exists for hosts that can't perform xHCI 1.0 Soft Retry
correctly, but it's only reachable from xhci-pci, matched against two AMD
Promontory PCI ids. Platform hosts have no way to ask for it.

Add it as a device property, the same way as quirk-broken-port-ped and its
neighbors. It's opt-in, so no existing platform is affected.

Needed for the Synopsys DWC3 on a Qualcomm IPQ4019, whose command ring
wedges when a Stop Endpoint command lands on a just-soft-retry-reset
endpoint -- exactly what unplugging a device mid-transfer triggers:

xhci-hcd xhci-hcd.1.auto: xHCI host not responding to stop endpoint command
xhci-hcd xhci-hcd.1.auto: xHCI host controller not responding, assume dead
xhci-hcd xhci-hcd.1.auto: HC died; cleaning up

Signed-off-by: Matt Eaton <linux@xxxxxxxxxxxxxx>
---
 drivers/usb/host/xhci-plat.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index 6fd595f81a30..22057493f935 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -265,6 +265,9 @@ int xhci_plat_probe(struct platform_device *pdev, struct device *sysdev, const s
 		if (device_property_read_bool(tmpdev, "quirk-broken-port-ped"))
 			xhci->quirks |= XHCI_BROKEN_PORT_PED;
 
+		if (device_property_read_bool(tmpdev, "xhci-no-soft-retry-quirk"))
+			xhci->quirks |= XHCI_NO_SOFT_RETRY;
+
 		if (device_property_read_bool(tmpdev, "xhci-sg-trb-cache-size-quirk"))
 			xhci->quirks |= XHCI_SG_TRB_CACHE_SIZE_QUIRK;
 

-- 
2.43.0