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authorRoger Quadros2017-10-31 15:11:55 +0200
committerFelipe Balbi2017-12-11 12:36:53 +0200
commit42bf02ec6e420e541af9a47437d0bdf961ca2972 (patch)
treed26f219a5d67aad75da1ec0db2e7a71fe0164352 /Documentation/devicetree/bindings/usb
parentd855e08cf623835bc3208209cd9ab32d6c710162 (diff)
usb: dwc3: Allow disabling of metastability workaround
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 <rogerq@ti.com> Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Diffstat (limited to 'Documentation/devicetree/bindings/usb')
-rw-r--r--Documentation/devicetree/bindings/usb/dwc3.txt2
1 files changed, 2 insertions, 0 deletions
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