diff options
| author | Alan Stern <stern@rowland.harvard.edu> | 2011-10-12 10:39:14 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-11-11 09:35:17 -0800 |
| commit | 21f25cdb9e476c64d504981133d0552f7d155805 (patch) | |
| tree | 0f364e86f1e89a74020d024516560de474740c71 /drivers/usb/host/ehci-hcd.c | |
| parent | 7eede2cbc1066124a0a4fee4d9671e28f7c62277 (diff) | |
EHCI: workaround for MosChip controller bug
commit 68aa95d5d4de31c9348c1628ffa85c805305ebc5 upstream.
This patch (as1489) works around a hardware bug in MosChip EHCI
controllers. Evidently when one of these controllers increments the
frame-index register, it changes the three low-order bits (the
microframe counter) before changing the higher order bits (the frame
counter). If the register is read at just the wrong time, the value
obtained is too low by 8.
When the appropriate quirk flag is set, we work around this problem by
reading the frame-index register a second time if the first value's
three low-order bits are all 0. This gives the hardware a chance to
finish updating the register, yielding the correct value.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Jason N Pitt <jpitt@fhcrc.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/host/ehci-hcd.c')
| -rw-r--r-- | drivers/usb/host/ehci-hcd.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c index c45a116f50fe..b27ceab17743 100644 --- a/drivers/usb/host/ehci-hcd.c +++ b/drivers/usb/host/ehci-hcd.c @@ -1188,8 +1188,7 @@ ehci_endpoint_reset(struct usb_hcd *hcd, struct usb_host_endpoint *ep) static int ehci_get_frame (struct usb_hcd *hcd) { struct ehci_hcd *ehci = hcd_to_ehci (hcd); - return (ehci_readl(ehci, &ehci->regs->frame_index) >> 3) % - ehci->periodic_size; + return (ehci_read_frame_index(ehci) >> 3) % ehci->periodic_size; } /*-------------------------------------------------------------------------*/ |