usb: dwc2: retry NAK'd interrupt transfers
authorStephen Warren <swarren@wwwdotorg.org>
Sun, 12 Apr 2015 03:52:02 +0000 (21:52 -0600)
committerMarek Vasut <marex@denx.de>
Tue, 14 Apr 2015 03:47:59 +0000 (05:47 +0200)
commit5877de916510cc2030eafe3761a835726956c7d3
treed78f4932cc2460676820798e95728d6d7b418c70
parente236519b7365ef75c5da6a5623f0b03d9c00cfae
usb: dwc2: retry NAK'd interrupt transfers

IIUC, interrupt transfers are NAK'd by devices until they wish to trigger
an interrupt, and e.g. EHCI controllers retry these in HW until they are
ACK'd. However, DWC2 doesn't seem to retry, so we need to do this in SW.
In practice, I've seen DWC2_HCINT_FRMOVRUN happen too. I'm not quite sure
what this error implies; perhaps it's related to how near the end of a
USB frame we're at when the interrupt transfer is initiated? Anyway,
retrying this temporary error seems to be necessary too.

With all these commits applied, both my USB keyboards (one LS Lenovo and
one FS Dell) work correctly when there is no USB hub between the SoC and
the keyboard; We still need split transactions to be implemented for hubs
to work.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
drivers/usb/host/dwc2.c