net: ipa: fix a bug in ipa_endpoint_stop()

In ipa_endpoint_stop(), for TX endpoints we set the number of retries
to 0.  When we break out of the loop, retries being 0 means we return
EIO rather than the value of ret (which should be 0).

Fix this by using a non-zero retry count for both RX and TX
channels, and just break out of the loop after calling
gsi_channel_stop() for TX channels.  This way only RX channels
will retry, and the retry count will be non-zero at the end
for TX channels (so the proper value gets returned).
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 713b6ebb)
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ipa/ipa_endpoint.c

@@ -1311,7 +1311,7 @@ static int ipa_endpoint_stop_rx_dma(struct ipa *ipa)
  */
 int ipa_endpoint_stop(struct ipa_endpoint *endpoint)
 {
-	u32 retries = endpoint->toward_ipa ? 0 : IPA_ENDPOINT_STOP_RX_RETRIES;
+	u32 retries = IPA_ENDPOINT_STOP_RX_RETRIES;
 	int ret;
 
 	do {
@@ -1319,12 +1319,9 @@ int ipa_endpoint_stop(struct ipa_endpoint *endpoint)
 		struct gsi *gsi = &ipa->gsi;
 
 		ret = gsi_channel_stop(gsi, endpoint->channel_id);
-		if (ret != -EAGAIN)
+		if (ret != -EAGAIN || endpoint->toward_ipa)
 			break;
 
-		if (endpoint->toward_ipa)
-			continue;
-
 		/* For IPA v3.5.1, send a DMA read task and check again */
 		if (ipa->version == IPA_VERSION_3_5_1) {
 			ret = ipa_endpoint_stop_rx_dma(ipa);