A Synopsys USB2.0 core used in Huawei Kunpeng920 SoC has a bug which
might cause the host controller not issuing ping.
Bug description:
After indicating an Interrupt on Async Advance, the software uses the
doorbell mechanism to delete the Next Link queue head of the last
executed queue head. At this time, the host controller still references
the removed queue head(the queue head is NULL). NULL reference causes
the host controller to lose the USB device.
Solution:
After deleting the Next Link queue head, the software can write one of the
valid queue head addresses to the ASYNCLISTADDR register to allow
the host controller to get the valid queue head.
There are detailed instructions and solutions in this patch:
commit 2f7ac6c19997 ("USB: ehci: add workaround for Synopsys HC bug")
Signed-off-by: Longfang Liu <liulongfang@xxxxxxxxxx>
---
Changes in V2:
- updated comment message
drivers/usb/host/ehci-pci.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c
index 1a48ab1..7ff2cbd 100644
--- a/drivers/usb/host/ehci-pci.c
+++ b/drivers/usb/host/ehci-pci.c
@@ -216,6 +216,13 @@ static int ehci_pci_setup(struct usb_hcd *hcd)
ehci_info(ehci, "applying MosChip frame-index workaround\n");
ehci->frame_index_bug = 1;
break;
+ case PCI_VENDOR_ID_HUAWEI:
+ /* Synopsys HC bug */
+ if (pdev->device == 0xa239) {
+ ehci_info(ehci, "applying Synopsys HC workaround\n");
+ ehci->has_synopsys_hc_bug = 1;
+ }
+ break;
}
/* optional debug port, normally in the first BAR */
--
2.8.1
