diff mbox series

[1/1] usb: chipidea: udc: make controller hardware endpoint primed

Message ID 20211031031453.6670-1-peter.chen@kernel.org (mailing list archive)
State Accepted
Commit 05735f0854e1e2fc0dd266cc6f583fc79dfdd5d8
Headers show
Series [1/1] usb: chipidea: udc: make controller hardware endpoint primed | expand

Commit Message

Peter Chen Oct. 31, 2021, 3:14 a.m. UTC 
From: Piyush Mehta <piyush.mehta@xilinx.com>

Root-cause:
There is an issue like endpoint is not recognized as primed, when bus
have more pressure and the add dTD tripwire semaphore (ATDTW bit in
USBCMD register) that can cause the controller to ignore a dTD that is
added to a primed endpoint.
This issue observed with the Windows10 host machine.

Workaround:
The software must implement a periodic cycle, and check for each dTD,
if the endpoint is primed. It can do this by reading the corresponding
bits in the ENDPTPRIME and ENDPTSTAT registers. If these bits are read
at 0, the software needs to re-prime the endpoint by writing 1 to the
corresponding bit in the ENDPTPRIME register.

Added conditional revision check of 2.20[CI_REVISION_22].

Signed-off-by: Piyush Mehta <piyush.mehta@xilinx.com>
Signed-off-by: Peter Chen <peter.chen@kernel.org>
---
 drivers/usb/chipidea/udc.c | 8 ++++++++
 1 file changed, 8 insertions(+)
diff mbox series

Patch

diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
index 8834ca613721..f9ca5010f65b 100644
--- a/drivers/usb/chipidea/udc.c
+++ b/drivers/usb/chipidea/udc.c
@@ -49,6 +49,8 @@  ctrl_endpt_in_desc = {
 	.wMaxPacketSize  = cpu_to_le16(CTRL_PAYLOAD_MAX),
 };
 
+static int reprime_dtd(struct ci_hdrc *ci, struct ci_hw_ep *hwep,
+		       struct td_node *node);
 /**
  * hw_ep_bit: calculates the bit number
  * @num: endpoint number
@@ -599,6 +601,12 @@  static int _hardware_enqueue(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq)
 
 		prevlastnode->ptr->next = cpu_to_le32(next);
 		wmb();
+
+		if (ci->rev == CI_REVISION_22) {
+			if (!hw_read(ci, OP_ENDPTSTAT, BIT(n)))
+				reprime_dtd(ci, hwep, prevlastnode);
+		}
+
 		if (hw_read(ci, OP_ENDPTPRIME, BIT(n)))
 			goto done;
 		do {