From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S932321AbdJZLte (ORCPT <rfc822;w@1wt.eu>);
        Thu, 26 Oct 2017 07:49:34 -0400
Received: from us01smtprelay-2.synopsys.com ([198.182.60.111]:60052 "EHLO
        smtprelay.synopsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1751705AbdJZLtc (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 26 Oct 2017 07:49:32 -0400
Subject: Re: [PATCH net] net: stmmac: First Queue must always be in DCB mode
To: Bhadram Varka <vbhadram@nvidia.com>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <d0f29981af9cfc700709af274acd7dba4b2014a7.1509008601.git.joabreu@synopsys.com>
 <c58a62cc2971476b95e34096eb32f852@bgmail102.nvidia.com>
CC: Joao Pinto <Joao.Pinto@synopsys.com>,
        "David S. Miller" <davem@davemloft.net>,
        Giuseppe Cavallaro <peppe.cavallaro@st.com>,
        Alexandre Torgue <alexandre.torgue@st.com>
From: Jose Abreu <Jose.Abreu@synopsys.com>
Message-ID: <73ccf81c-6865-9e02-83e1-5ba1e4d5e918@synopsys.com>
Date: Thu, 26 Oct 2017 12:49:26 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101
 Thunderbird/45.4.0
MIME-Version: 1.0
In-Reply-To: <c58a62cc2971476b95e34096eb32f852@bgmail102.nvidia.com>
Content-Type: text/plain; charset="windows-1252"
Content-Transfer-Encoding: 7bit
X-Originating-IP: [10.107.19.60]
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Hi Bhadram,

On 26-10-2017 11:51, Bhadram Varka wrote:
> Hi Jose,
>
>> -----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
>> <Joao.Pinto@synopsys.com>; David S. Miller <davem@davemloft.net>;
>> Giuseppe Cavallaro <peppe.cavallaro@st.com>; Alexandre Torgue
>> <alexandre.torgue@st.com>
>> 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 <joabreu@synopsys.com>
>> Cc: Joao Pinto <jpinto@synopsys.com>
>> Cc: David S. Miller <davem@davemloft.net>
>> Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>
>> Cc: Alexandre Torgue <alexandre.torgue@st.com>
>> ---
>>  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.