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, when has_synopsys_hc_bug set
to 1，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. in order to solve that problem, this patch set
the flag for Huawei Kunpeng920
There are detailed instructions and solutions in this patch:
commit 2f7ac6c199 ("USB: ehci: add workaround for Synopsys HC bug")
Signed-off-by: Longfang Liu <liulongfang@huawei.com>
Cc: stable <stable@vger.kernel.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/1591588019-44284-1-git-send-email-liulongfang@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1ddcb71a3e