Re: [PATCH 1/6] DM USB: xHCI: fix an xHCI issue to enable UOS s3 feature

Yu Wang

Acked-by: Yu Wang <>

On 18-08-13 16:48:30, Wu, Xiaoguang wrote:
Current DM design use two variables to do the indexing of xHCI
Event Ring: er_enq_idx and er_events_cnt. They are members of
the struct pci_xhci_rtsregs.

In UOS, during the process of xHCI resuming, the xHCI driver
will restore the ERSTBA (Event Ring Segment Table Base Address)
register to be the value before suspending. And at this point,
the old DM implementation will set both er_enq_idx and
er_events_cnt to be zero, so the DM will access the Event Ring
from the start position in the buffer. But at the same time the
UOS xHCI driver still wants to access the old position in the
Event Ring before suspending, which will result of unexpected

Signed-off-by: Xiaoguang Wu <xiaoguang.wu@...>
Reviewed-by: Liang Yang <liang3.yang@...>
devicemodel/hw/pci/xhci.c | 3 ---
1 file changed, 3 deletions(-)

diff --git a/devicemodel/hw/pci/xhci.c b/devicemodel/hw/pci/xhci.c
index da0c42a..792d930 100644
--- a/devicemodel/hw/pci/xhci.c
+++ b/devicemodel/hw/pci/xhci.c
@@ -2732,9 +2732,6 @@ pci_xhci_rtsregs_write(struct pci_xhci_vdev *xdev,
rts->erst_p = XHCI_GADDR(xdev,
xdev->rtsregs.erstba_p->qwEvrsTablePtr & ~0x3FUL);

- rts->er_enq_idx = 0;
- rts->er_events_cnt = 0;
UPRINTF(LDBG, "wr erstba erst (%p) ptr 0x%lx, sz %u\r\n",

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