[PATCH net] net: dsa: microchip: Fix wrong rx drop MIB counter for KSZ8863

[PATCH net] net: dsa: microchip: Fix wrong rx drop MIB counter for KSZ8863

[Tristram.Ha]

From: Tristram Ha <tristram.ha@microchip.com>

When KSZ8863 support was first added to KSZ driver the RX drop MIB
counter was somehow defined as 0x105.  The TX drop MIB counter
starts at 0x100 for port 1, 0x101 for port 2, and 0x102 for port 3, so
the RX drop MIB counter should start at 0x103 for port 1, 0x104 for
port 2, and 0x105 for port 3.

There are 5 ports for KSZ8895, so its RX drop MIB counter starts at
0x105.

Fixes: 4b20a07e103f ("net: dsa: microchip: ksz8795: add support for ksz88xx chips")
Signed-off-by: Tristram Ha <tristram.ha@microchip.com>
---
 drivers/net/dsa/microchip/ksz8.c     | 3 +++
 drivers/net/dsa/microchip/ksz8_reg.h | 4 +++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/dsa/microchip/ksz8.c b/drivers/net/dsa/microchip/ksz8.c
index be433b4e2b1c..8f55be89f8bf 100644
--- a/drivers/net/dsa/microchip/ksz8.c
+++ b/drivers/net/dsa/microchip/ksz8.c
@@ -371,6 +371,9 @@ static void ksz8863_r_mib_pkt(struct ksz_device *dev, int port, u16 addr,
 	addr -= dev->info->reg_mib_cnt;
 	ctrl_addr = addr ? KSZ8863_MIB_PACKET_DROPPED_TX_0 :
 			   KSZ8863_MIB_PACKET_DROPPED_RX_0;
+	if (ksz_is_8895_family(dev) &&
+	    ctrl_addr == KSZ8863_MIB_PACKET_DROPPED_RX_0)
+		ctrl_addr = KSZ8895_MIB_PACKET_DROPPED_RX_0;
 	ctrl_addr += port;
 	ctrl_addr |= IND_ACC_TABLE(TABLE_MIB | TABLE_READ);
 
diff --git a/drivers/net/dsa/microchip/ksz8_reg.h b/drivers/net/dsa/microchip/ksz8_reg.h
index 329688603a58..da80e659c648 100644
--- a/drivers/net/dsa/microchip/ksz8_reg.h
+++ b/drivers/net/dsa/microchip/ksz8_reg.h
@@ -784,7 +784,9 @@
 #define KSZ8795_MIB_TOTAL_TX_1		0x105
 
 #define KSZ8863_MIB_PACKET_DROPPED_TX_0 0x100
-#define KSZ8863_MIB_PACKET_DROPPED_RX_0 0x105
+#define KSZ8863_MIB_PACKET_DROPPED_RX_0 0x103
+
+#define KSZ8895_MIB_PACKET_DROPPED_RX_0 0x105
 
 #define MIB_PACKET_DROPPED		0x0000FFFF
 
-- 
2.34.1

Re: [PATCH net] net: dsa: microchip: Fix wrong rx drop MIB counter for KSZ8863

[Oleksij Rempel]

Hi Tristram,

On Tue, Jul 22, 2025 at 08:04:03PM -0700, Tristram.Ha@microchip.com wrote:
> From: Tristram Ha <tristram.ha@microchip.com>
> 
> When KSZ8863 support was first added to KSZ driver the RX drop MIB
> counter was somehow defined as 0x105.  The TX drop MIB counter
> starts at 0x100 for port 1, 0x101 for port 2, and 0x102 for port 3, so
> the RX drop MIB counter should start at 0x103 for port 1, 0x104 for
> port 2, and 0x105 for port 3.
> 
> There are 5 ports for KSZ8895, so its RX drop MIB counter starts at
> 0x105.
> 
> Fixes: 4b20a07e103f ("net: dsa: microchip: ksz8795: add support for ksz88xx chips")
> Signed-off-by: Tristram Ha <tristram.ha@microchip.com>

Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>

Thank you for your patch!

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Re: [PATCH net] net: dsa: microchip: Fix wrong rx drop MIB counter for KSZ8863

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Tue, 22 Jul 2025 20:04:03 -0700 you wrote:
> From: Tristram Ha <tristram.ha@microchip.com>
> 
> When KSZ8863 support was first added to KSZ driver the RX drop MIB
> counter was somehow defined as 0x105.  The TX drop MIB counter
> starts at 0x100 for port 1, 0x101 for port 2, and 0x102 for port 3, so
> the RX drop MIB counter should start at 0x103 for port 1, 0x104 for
> port 2, and 0x105 for port 3.
> 
> [...]

Here is the summary with links:
  - [net] net: dsa: microchip: Fix wrong rx drop MIB counter for KSZ8863
    https://git.kernel.org/netdev/net/c/165a7f5db919

You are awesome, thank you!
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