usb: dwc2: host: fix split transfer schedule sequence

We're supposed to keep outstanding splits in order.  Keep track of a
list of the order of splits and process channel interrupts in that
order.

Without this change and the following setup:
* Rockchip rk3288 Chromebook, using port ff540000
  -> Pluggable 7-port Hub with Charging (powered)
     -> Microsoft Wireless Keyboard 2000 in port 1.
     -> Das Keyboard in port 2.

...I find that I get dropped keys on the Microsoft keyboard (I'm sure
there are other combinations that fail, but this documents my test).
Specifically I've been typing "hahahahahahaha" on the keyboard and often
see keys dropped or repeated.

After this change the above setup works properly.  This patch is based
on a previous patch proposed by Yunzhi Li ("usb: dwc2: hcd: fix periodic
transfer schedule sequence")

Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Yunzhi Li <lyz@rock-chips.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Kever Yang <kever.yang@rock-chips.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
index 7fb6434f4639..538cf38af0e4 100644
--- a/drivers/usb/dwc2/core.h
+++ b/drivers/usb/dwc2/core.h
@@ -657,6 +657,7 @@ struct dwc2_hregs_backup {
  *                      periodic_sched_ready because it must be rescheduled for
  *                      the next frame. Otherwise, the item moves to
  *                      periodic_sched_inactive.
+ * @split_order:        List keeping track of channels doing splits, in order.
  * @periodic_usecs:     Total bandwidth claimed so far for periodic transfers.
  *                      This value is in microseconds per (micro)frame. The
  *                      assumption is that all periodic transfers may occur in
@@ -780,6 +781,7 @@ struct dwc2_hsotg {
 	struct list_head periodic_sched_ready;
 	struct list_head periodic_sched_assigned;
 	struct list_head periodic_sched_queued;
+	struct list_head split_order;
 	u16 periodic_usecs;
 	u16 frame_usecs[8];
 	u16 frame_number;