1 files changed, 25 insertions, 9 deletions

diff --git a/drivers/platform/surface/aggregator/ssh_packet_layer.c b/drivers/platform/surface/aggregator/ssh_packet_layer.c
index 8a4451c1ffe5..3dd22856570f 100644
--- a/drivers/platform/surface/aggregator/ssh_packet_layer.c
+++ b/drivers/platform/surface/aggregator/ssh_packet_layer.c
@@ -2,10 +2,10 @@
 /*
  * SSH packet transport layer.
  *
- * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2019-2022 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
-#include <asm/unaligned.h>
+#include <linux/unaligned.h>
 #include <linux/atomic.h>
 #include <linux/error-injection.h>
 #include <linux/jiffies.h>
@@ -671,7 +671,7 @@ static void ssh_ptl_timeout_reaper_mod(struct ssh_ptl *ptl, ktime_t now,
 	/* Re-adjust / schedule reaper only if it is above resolution delta. */
 	if (ktime_before(aexp, ptl->rtx_timeout.expires)) {
 		ptl->rtx_timeout.expires = expires;
-		mod_delayed_work(system_wq, &ptl->rtx_timeout.reaper, delta);
+		mod_delayed_work(system_percpu_wq, &ptl->rtx_timeout.reaper, delta);
 	}
 
 	spin_unlock(&ptl->rtx_timeout.lock);
@@ -1596,16 +1596,32 @@ static void ssh_ptl_timeout_reap(struct work_struct *work)
 		ssh_ptl_tx_wakeup_packet(ptl);
 }
 
-static bool ssh_ptl_rx_retransmit_check(struct ssh_ptl *ptl, u8 seq)
+static bool ssh_ptl_rx_retransmit_check(struct ssh_ptl *ptl, const struct ssh_frame *frame)
 {
 	int i;
 
 	/*
+	 * Ignore unsequenced packets. On some devices (notably Surface Pro 9),
+	 * unsequenced events will always be sent with SEQ=0x00. Attempting to
+	 * detect retransmission would thus just block all events.
+	 *
+	 * While sequence numbers would also allow detection of retransmitted
+	 * packets in unsequenced communication, they have only ever been used
+	 * to cover edge-cases in sequenced transmission. In particular, the
+	 * only instance of packets being retransmitted (that we are aware of)
+	 * is due to an ACK timeout. As this does not happen in unsequenced
+	 * communication, skip the retransmission check for those packets
+	 * entirely.
+	 */
+	if (frame->type == SSH_FRAME_TYPE_DATA_NSQ)
+		return false;
+
+	/*
 	 * Check if SEQ has been seen recently (i.e. packet was
 	 * re-transmitted and we should ignore it).
 	 */
 	for (i = 0; i < ARRAY_SIZE(ptl->rx.blocked.seqs); i++) {
-		if (likely(ptl->rx.blocked.seqs[i] != seq))
+		if (likely(ptl->rx.blocked.seqs[i] != frame->seq))
 			continue;
 
 		ptl_dbg(ptl, "ptl: ignoring repeated data packet\n");
@@ -1613,7 +1629,7 @@ static bool ssh_ptl_rx_retransmit_check(struct ssh_ptl *ptl, u8 seq)
 	}
 
 	/* Update list of blocked sequence IDs. */
-	ptl->rx.blocked.seqs[ptl->rx.blocked.offset] = seq;
+	ptl->rx.blocked.seqs[ptl->rx.blocked.offset] = frame->seq;
 	ptl->rx.blocked.offset = (ptl->rx.blocked.offset + 1)
 				  % ARRAY_SIZE(ptl->rx.blocked.seqs);
 
@@ -1624,7 +1640,7 @@ static void ssh_ptl_rx_dataframe(struct ssh_ptl *ptl,
 				 const struct ssh_frame *frame,
 				 const struct ssam_span *payload)
 {
-	if (ssh_ptl_rx_retransmit_check(ptl, frame->seq))
+	if (ssh_ptl_rx_retransmit_check(ptl, frame))
 		return;
 
 	ptl->ops.data_received(ptl, payload);
@@ -1871,9 +1887,9 @@ int ssh_ptl_rx_stop(struct ssh_ptl *ptl)
  * Return: Returns the number of bytes transferred (positive or zero) on
  * success. Returns %-ESHUTDOWN if the packet layer has been shut down.
  */
-int ssh_ptl_rx_rcvbuf(struct ssh_ptl *ptl, const u8 *buf, size_t n)
+ssize_t ssh_ptl_rx_rcvbuf(struct ssh_ptl *ptl, const u8 *buf, size_t n)
 {
-	int used;
+	size_t used;
 
 	if (test_bit(SSH_PTL_SF_SHUTDOWN_BIT, &ptl->state))
 		return -ESHUTDOWN;