usb: gadget: net2280: Add workaround for AB chip Errata 11

The errata description is:

Workaround for Default Duration of LFPS Handshake Signaling for
Device-Initiated U1 Exit is too short.

The default duration of the LFPS handshake generated by USB3380 for a device-initiated U1-exit may not be
long enough for certain SuperSpeed downstream ports (SuperSpeed hubs/hosts) to recognize. This could lead
to USB3380 entering the recovery state pre-maturely and ending up in the SS.Inactive state.

I have observed various enumeration failures, seemingly related to
lost transactions or SETUP status phases on modern hosts (typically
thunderbolt capable systems) without this workaround.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

diff --git a/drivers/usb/gadget/udc/net2280.c b/drivers/usb/gadget/udc/net2280.c
index e0191146ba22ac06c171f7a39d38f5ef094bdea6..51efee21915ff12586dfe43c54ec8e682ec5cacc 100644 (file)
--- a/drivers/usb/gadget/udc/net2280.c
+++ b/drivers/usb/gadget/udc/net2280.c
@@ -2269,6 +2269,16 @@ static void usb_reinit_338x(struct net2280 *dev)
        val |= 0x3 << HOT_RX_RESET_TS2;
        writel(val, &dev->llregs->ll_tsn_counters_3);
 
+       /*
+        * AB errata. Errata 11. Workaround for Default Duration of LFPS
+        * Handshake Signaling for Device-Initiated U1 Exit is too short.
+        * Without this, various enumeration failures observed with
+        * modern superspeed hosts.
+        */
+       val = readl(&dev->llregs->ll_lfps_timers_2);
+       writel((val & 0xffff0000) | LFPS_TIMERS_2_WORKAROUND_VALUE,
+              &dev->llregs->ll_lfps_timers_2);
+
        /*
         * Set Recovery Idle to Recover bit:
         * - On SS connections, setting Recovery Idle to Recover Fmw improves