Re: [PATCH net] net: stmmac: First Queue must always be in DCB mode

Hi Bhadram,

On 26-10-2017 11:51, Bhadram Varka wrote:

Hi Jose,

quoted

-----Original Message-----
From: netdev-owner@vger.kernel.org [mailto:netdev-
owner@vger.kernel.org] On Behalf Of Jose Abreu
Sent: Thursday, October 26, 2017 2:37 PM
To: netdev@vger.kernel.org; linux-kernel@vger.kernel.org
Cc: Jose Abreu <Jose.Abreu@synopsys.com>; Joao Pinto
[off-list ref]; David S. Miller [off-list ref];
Giuseppe Cavallaro [off-list ref]; Alexandre Torgue
[off-list ref]
Subject: [PATCH net] net: stmmac: First Queue must always be in DCB mode

According to DWMAC databook the first queue operating mode must always
be in DCB.

As MTL_QUEUE_DCB = 1, we need to always set the first queue operating
mode to DCB otherwise driver will think that queue is in AVB mode (because
MTL_QUEUE_AVB = 0).

Signed-off-by: Jose Abreu <redacted>
Cc: Joao Pinto <redacted>
Cc: David S. Miller <davem@davemloft.net>
Cc: Giuseppe Cavallaro <redacted>
Cc: Alexandre Torgue <redacted>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c

b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index 21f59fe..603225b 100644

--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c

@@ -150,6 +150,13 @@ static void stmmac_mtl_setup(struct

platform_device *pdev,
 	plat->rx_queues_to_use = 1;
 	plat->tx_queues_to_use = 1;

+	/* First Queue must always be in DCB mode. As MTL_QUEUE_DCB =
1 we need
+	 * to always set this, otherwise Queue will be classified as AVB
+	 * (because MTL_QUEUE_AVB = 0).
+	 */

Its better if we can check whether IP HW features (register - 0x120) supports the DCB or not. If yes, then set the DCB mode.
There is possibility that DCB feature not enable for few of the Synopsys IP's.

A queue can either be in Generic/DCB or AVB mode. The sequence to
enable a DCB or a Generic queue is the same so there is no need
to check for DCB capability in HW.

Best Regards,
Jose Miguel Abreu

Thanks,
Bhadram.