tty: n_smux: Adjust receive retry queue parameters
If the remote modem has queued many small packets in the UART FIFO and
the SMUX client cannot provide receive buffers fast enough, then the
auto flow control command may not get processed before the receive queue
has overflowed. In measured cases, an average of 10 packets are
received after flow control is enabled. In the failure cases, up to 19
packets are received which is more than the max queue size (32 packets)
minus the high watermark (16 packets) which causes an overflow.
Use a bigger retry queue and more aggressive watermark values to make
auto flow control more responsive and to allow more packets to get
queued before an overflow occurs.
CRs-Fixed: 394198
Signed-off-by: Eric Holmberg <eholmber@codeaurora.org>
(cherry picked from commit 0ab6fc1757ae275a7e29c95588c8470fb787ee2a)
Change-Id: I20817f4dab3360f3c62bd83e74594555571a3a9f
Signed-off-by: Sudhir Sharma <sudsha@codeaurora.org>
diff --git a/drivers/tty/smux_private.h b/drivers/tty/smux_private.h
index 353c762..4c901c0 100644
--- a/drivers/tty/smux_private.h
+++ b/drivers/tty/smux_private.h
@@ -31,11 +31,11 @@
#define SMUX_UT_ECHO_ACK_FAIL 0xF2
/* Maximum number of packets in retry queue */
-#define SMUX_RX_RETRY_MAX_PKTS 32
-#define SMUX_RX_WM_HIGH 16
-#define SMUX_RX_WM_LOW 4
-#define SMUX_TX_WM_LOW 2
-#define SMUX_TX_WM_HIGH 4
+#define SMUX_RX_RETRY_MAX_PKTS 128
+#define SMUX_RX_WM_HIGH 4
+#define SMUX_RX_WM_LOW 0
+#define SMUX_TX_WM_LOW 2
+#define SMUX_TX_WM_HIGH 4
struct tty_struct;