From: Tom Barbette Subject: MLX5 should define the timestamp field in the doc Date: Tue, 4 Sep 2018 14:26:02 +0000 Message-ID: <1536071162684.44442@kth.se> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Cc: "shahafs@mellanox.com" , "yskoh@mellanox.com" , "john.mcnamara@intel.com" , "marko.kovacevic@intel.com" To: "dev@dpdk.org" Return-path: Received: from smtp-4.sys.kth.se (smtp-4.sys.kth.se [130.237.48.193]) by dpdk.org (Postfix) with ESMTP id E5FC31559 for ; Tue, 4 Sep 2018 16:26:28 +0200 (CEST) Content-Language: fr-FR List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Hi all, As far as I know, MLX5 is the only driver to support hardware timestamping. It would be great to update the doc to explain what the hardware timestamp = is supposed to be. If it's nanoseconds, then just a shift regarding system = time is enough ? Does it also need a multiplication? Can we query that from= hardware? Or provide a piece of code to be used. As it, the feature is use= less... It would be interesting to normalize the hardware timestamping. I guess for= any driver, an offset and a multiplication(shift+multiplier eventually) wo= uld be enough, and the API should be updated to provide a function to conve= rt a hardware timestamp to software (or that should be part of the driver a= nd done automatically if offloading is enabled?) and probably one to initia= lize the time, much like the Linux one at https://elixir.bootlin.com/linux/= v4.18.5/source/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c#L488 . Thanks, Tom ?