From c813b4467a2291d14dd9c90f9542ad55eb1ec315 Mon Sep 17 00:00:00 2001 From: Roger Quadros Date: Thu, 5 Sep 2019 10:17:45 -0600 Subject: usb: dwc3: Allow disabling of metastability workaround commit 42bf02ec6e420e541af9a47437d0bdf961ca2972 upstream Some platforms (e.g. TI's DRA7 USB2 instance) have more trouble with the metastability workaround as it supports only a High-Speed PHY and the PHY can enter into an Erratic state [1] when the controller is set in SuperSpeed mode as part of the metastability workaround. This causes upto 2 seconds delay in enumeration on DRA7's USB2 instance in gadget mode. If these platforms can be better off without the workaround, provide a device tree property to suggest that so the workaround is avoided. [1] Device mode enumeration trace showing PHY Erratic Error. irq/90-dwc3-969 [000] d... 52.323145: dwc3_event: event (00000901): Erratic Error [U0] irq/90-dwc3-969 [000] d... 52.560646: dwc3_event: event (00000901): Erratic Error [U0] irq/90-dwc3-969 [000] d... 52.798144: dwc3_event: event (00000901): Erratic Error [U0] Signed-off-by: Roger Quadros Signed-off-by: Felipe Balbi Signed-off-by: Mathieu Poirier Signed-off-by: Greg Kroah-Hartman --- Documentation/devicetree/bindings/usb/dwc3.txt | 2 ++ 1 file changed, 2 insertions(+) (limited to 'Documentation') diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt b/Documentation/devicetree/bindings/usb/dwc3.txt index 52fb41046b34..44e8bab159ad 100644 --- a/Documentation/devicetree/bindings/usb/dwc3.txt +++ b/Documentation/devicetree/bindings/usb/dwc3.txt @@ -47,6 +47,8 @@ Optional properties: from P0 to P1/P2/P3 without delay. - snps,dis-tx-ipgap-linecheck-quirk: when set, disable u2mac linestate check during HS transmit. + - snps,dis_metastability_quirk: when set, disable metastability workaround. + CAUTION: use only if you are absolutely sure of it. - snps,is-utmi-l1-suspend: true when DWC3 asserts output signal utmi_l1_suspend_n, false when asserts utmi_sleep_n - snps,hird-threshold: HIRD threshold -- cgit v1.2.3