net: dsa: rtl8366rb: Support the CPU DSA tag

This activates the support to use the CPU tag to properly
direct ingress traffic to the right port.

Bit 15 in register RTL8368RB_CPU_CTRL_REG can be set to
1 to disable the insertion of the CPU tag which is what
the code currently does. The bit 15 define calls this
setting RTL8368RB_CPU_INSTAG which is confusing since the
inverse meaning is implied: programmers may think that
setting this bit to 1 will *enable* inserting the tag
rather than disabling it, so rename this setting in
bit 15 to RTL8368RB_CPU_NO_TAG which is more to the
point.

After this e.g. ping works out-of-the-box with the
RTL8366RB.

Cc: DENG Qingfang <dqfext@gmail.com>
Cc: Mauri Sandberg <sandberg@mailfence.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/dsa/Kconfig b/drivers/net/dsa/Kconfig
index d0024cb..468b3c4 100644 (file)
--- a/drivers/net/dsa/Kconfig
+++ b/drivers/net/dsa/Kconfig
@@ -70,6 +70,7 @@ config NET_DSA_QCA8K
 config NET_DSA_REALTEK_SMI
        tristate "Realtek SMI Ethernet switch family support"
        depends on NET_DSA
+       select NET_DSA_TAG_RTL4_A
        select FIXED_PHY
        select IRQ_DOMAIN
        select REALTEK_PHY

diff --git a/drivers/net/dsa/rtl8366rb.c b/drivers/net/dsa/rtl8366rb.c
index fd19775..48f1ff7 100644 (file)
--- a/drivers/net/dsa/rtl8366rb.c
+++ b/drivers/net/dsa/rtl8366rb.c
@@ -109,8 +109,8 @@
 /* CPU port control reg */
 #define RTL8368RB_CPU_CTRL_REG         0x0061
 #define RTL8368RB_CPU_PORTS_MSK                0x00FF
-/* Enables inserting custom tag length/type 0x8899 */
-#define RTL8368RB_CPU_INSTAG           BIT(15)
+/* Disables inserting custom tag length/type 0x8899 */
+#define RTL8368RB_CPU_NO_TAG           BIT(15)
 
 #define RTL8366RB_SMAR0                        0x0070 /* bits 0..15 */
 #define RTL8366RB_SMAR1                        0x0071 /* bits 16..31 */
@@ -844,16 +844,14 @@ static int rtl8366rb_setup(struct dsa_switch *ds)
        if (ret)
                return ret;
 
-       /* Enable CPU port and enable inserting CPU tag
+       /* Enable CPU port with custom DSA tag 8899.
         *
-        * Disabling RTL8368RB_CPU_INSTAG here will change the behaviour
-        * of the switch totally and it will start talking Realtek RRCP
-        * internally. It is probably possible to experiment with this,
-        * but then the kernel needs to understand and handle RRCP first.
+        * If you set RTL8368RB_CPU_NO_TAG (bit 15) in this registers
+        * the custom tag is turned off.
         */
        ret = regmap_update_bits(smi->map, RTL8368RB_CPU_CTRL_REG,
                                 0xFFFF,
-                                RTL8368RB_CPU_INSTAG | BIT(smi->cpu_port));
+                                BIT(smi->cpu_port));
        if (ret)
                return ret;
 
@@ -967,21 +965,8 @@ static enum dsa_tag_protocol rtl8366_get_tag_protocol(struct dsa_switch *ds,
                                                      int port,
                                                      enum dsa_tag_protocol mp)
 {
-       /* For now, the RTL switches are handled without any custom tags.
-        *
-        * It is possible to turn on "custom tags" by removing the
-        * RTL8368RB_CPU_INSTAG flag when enabling the port but what it
-        * does is unfamiliar to DSA: ethernet frames of type 8899, the Realtek
-        * Remote Control Protocol (RRCP) start to appear on the CPU port of
-        * the device. So this is not the ordinary few extra bytes in the
-        * frame. Instead it appears that the switch starts to talk Realtek
-        * RRCP internally which means a pretty complex RRCP implementation
-        * decoding and responding the RRCP protocol is needed to exploit this.
-        *
-        * The OpenRRCP project (dormant since 2009) have reverse-egineered
-        * parts of the protocol.
-        */
-       return DSA_TAG_PROTO_NONE;
+       /* This switch uses the 4 byte protocol A Realtek DSA tag */
+       return DSA_TAG_PROTO_RTL4_A;
 }
 
 static void rtl8366rb_adjust_link(struct dsa_switch *ds, int port,