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Date:   Thu, 02 Jan 2020 16:33:02 -0800 (PST)
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Subject: Re: [v3,net-next] enetc: add support time specific departure base
 on the qos etf
From:   David Miller <davem@davemloft.net>
In-Reply-To: <20200102044300.29951-1-Po.Liu@nxp.com>
References: <20191227025547.4452-1-Po.Liu@nxp.com>
        <20200102044300.29951-1-Po.Liu@nxp.com>
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From: Po Liu <po.liu@nxp.com>
Date: Thu, 2 Jan 2020 04:59:24 +0000

> ENETC implement time specific departure capability, which enables
> the user to specify when a frame can be transmitted. When this
> capability is enabled, the device will delay the transmission of
> the frame so that it can be transmitted at the precisely specified time.
> The delay departure time up to 0.5 seconds in the future. If the
> departure time in the transmit BD has not yet been reached, based
> on the current time, the packet will not be transmitted.
> 
> This driver was loaded by Qos driver ETF. User could load it by tc
> commands. Here are the example commands:
> 
> tc qdisc add dev eth0 root handle 1: mqprio \
> 	   num_tc 8 map 0 1 2 3 4 5 6 7 hw 1
> tc qdisc replace dev eth0 parent 1:8 etf \
> 	   clockid CLOCK_TAI delta 30000  offload
> 
> These example try to set queue mapping first and then set queue 7
> with 30us ahead dequeue time.
> 
> Then user send test frame should set SO_TXTIME feature for socket.
> 
> There are also some limitations for this feature in hardware:
> - Transmit checksum offloads and time specific departure operation
> are mutually exclusive.
> - Time Aware Shaper feature (Qbv) offload and time specific departure
> operation are mutually exclusive.
> 
> Signed-off-by: Po Liu <Po.Liu@nxp.com>
> Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> ---
> Changes v2-v3:
> - Avoid tx checking sum offload when setting TXTIME offload. This is
> not support in hardware.

This looks a lot better, applied, thank you.