r8169: skip DASH fw status checks when DASH is disabled

On devices that support DASH, the current code in the "rtl_loop_wait" function
raises false alarms when DASH is disabled. This occurs because the function
attempts to wait for the DASH firmware to be ready, even though it's not
relevant in this case.

r8169 0000:0c:00.0 eth0: RTL8168ep/8111ep, 38:7c:76:49:08:d9, XID 502, IRQ 86
r8169 0000:0c:00.0 eth0: jumbo features [frames: 9194 bytes, tx checksumming: ko]
r8169 0000:0c:00.0 eth0: DASH disabled
...
r8169 0000:0c:00.0 eth0: rtl_ep_ocp_read_cond == 0 (loop: 30, delay: 10000).

This patch modifies the driver start/stop functions to skip checking the DASH
firmware status when DASH is explicitly disabled. This prevents unnecessary
delays and false alarms.

The patch has been tested on several ThinkStation P8/PX workstations.

Fixes: 0ab0c45d ("r8169: add handling DASH when DASH is disabled")
Signed-off-by: Atlas Yu <atlas.yu@canonical.com>
Reviewed-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/20240328055152.18443-1-atlas.yu@canonical.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/realtek/r8169_main.c

@@ -1314,17 +1314,40 @@ static void rtl8168ep_stop_cmac(struct rtl8169_private *tp)
 	RTL_W8(tp, IBCR0, RTL_R8(tp, IBCR0) & ~0x01);
 }
 
+static void rtl_dash_loop_wait(struct rtl8169_private *tp,
+			       const struct rtl_cond *c,
+			       unsigned long usecs, int n, bool high)
+{
+	if (!tp->dash_enabled)
+		return;
+	rtl_loop_wait(tp, c, usecs, n, high);
+}
+
+static void rtl_dash_loop_wait_high(struct rtl8169_private *tp,
+				    const struct rtl_cond *c,
+				    unsigned long d, int n)
+{
+	rtl_dash_loop_wait(tp, c, d, n, true);
+}
+
+static void rtl_dash_loop_wait_low(struct rtl8169_private *tp,
+				   const struct rtl_cond *c,
+				   unsigned long d, int n)
+{
+	rtl_dash_loop_wait(tp, c, d, n, false);
+}
+
 static void rtl8168dp_driver_start(struct rtl8169_private *tp)
 {
 	r8168dp_oob_notify(tp, OOB_CMD_DRIVER_START);
-	rtl_loop_wait_high(tp, &rtl_dp_ocp_read_cond, 10000, 10);
+	rtl_dash_loop_wait_high(tp, &rtl_dp_ocp_read_cond, 10000, 10);
 }
 
 static void rtl8168ep_driver_start(struct rtl8169_private *tp)
 {
 	r8168ep_ocp_write(tp, 0x01, 0x180, OOB_CMD_DRIVER_START);
 	r8168ep_ocp_write(tp, 0x01, 0x30, r8168ep_ocp_read(tp, 0x30) | 0x01);
-	rtl_loop_wait_high(tp, &rtl_ep_ocp_read_cond, 10000, 30);
+	rtl_dash_loop_wait_high(tp, &rtl_ep_ocp_read_cond, 10000, 30);
 }
 
 static void rtl8168_driver_start(struct rtl8169_private *tp)
@@ -1338,7 +1361,7 @@ static void rtl8168_driver_start(struct rtl8169_private *tp)
 static void rtl8168dp_driver_stop(struct rtl8169_private *tp)
 {
 	r8168dp_oob_notify(tp, OOB_CMD_DRIVER_STOP);
-	rtl_loop_wait_low(tp, &rtl_dp_ocp_read_cond, 10000, 10);
+	rtl_dash_loop_wait_low(tp, &rtl_dp_ocp_read_cond, 10000, 10);
 }
 
 static void rtl8168ep_driver_stop(struct rtl8169_private *tp)
@@ -1346,7 +1369,7 @@ static void rtl8168ep_driver_stop(struct rtl8169_private *tp)
 	rtl8168ep_stop_cmac(tp);
 	r8168ep_ocp_write(tp, 0x01, 0x180, OOB_CMD_DRIVER_STOP);
 	r8168ep_ocp_write(tp, 0x01, 0x30, r8168ep_ocp_read(tp, 0x30) | 0x01);
-	rtl_loop_wait_low(tp, &rtl_ep_ocp_read_cond, 10000, 10);
+	rtl_dash_loop_wait_low(tp, &rtl_ep_ocp_read_cond, 10000, 10);
 }
 
 static void rtl8168_driver_stop(struct rtl8169_private *tp)