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[23.128.96.18]) by mx.google.com with ESMTP id cb6si934390ejb.459.2021.01.12.02.25.44; Tue, 12 Jan 2021 02:26:07 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405130AbhALAZO (ORCPT + 99 others); Mon, 11 Jan 2021 19:25:14 -0500 Received: from mail-yb1-f181.google.com ([209.85.219.181]:33122 "EHLO mail-yb1-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404219AbhALABZ (ORCPT ); Mon, 11 Jan 2021 19:01:25 -0500 Received: by mail-yb1-f181.google.com with SMTP id o144so526977ybc.0; Mon, 11 Jan 2021 16:01:09 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=WYFvp4pRAM4I/ettmtAye/8Q4IbY3OpbPnErkgoce1U=; b=OAHGanJiW1cArupnEBR8NfBR2WjUwgS3dXjbElol9ZSNHBHL+eBYDVqrFWR22MnERr 4k4aS7O6nv4zDe5KK/s6jTpxAiS2s7JUGkf8nkaTuG32nMIHCiYz0gA6r5qCeCDPrFw2 2V0asE6R8OTsCKUepwZeMUldbGEOsEO4QpzFKfLry/JvU/1hNnFotXk++W28UWJzkR1F KhE2l4HR64WPTQVMj28TIWyhir/mD9RIoooLFvyWYrF33IrIuwvjl/RvwFcwgdi2UPkQ +E9SRppB9DVgD0BF655ylTHsmKtR2fApzKY3Lak5nnx75F0oSZSOeXrNi1tT8tW+ZQwB K6DQ== X-Gm-Message-State: AOAM533mB8I9pPOJLAMux7db2iSO1+w6vVD8VaVp/1AxO+QzDLx++Hc4 6hrYKcBujH3PIPrvzsIVuxJ7dgt8mN8clMGe08w= X-Received: by 2002:a05:6902:4f4:: with SMTP id w20mr3149495ybs.125.1610409643862; Mon, 11 Jan 2021 16:00:43 -0800 (PST) MIME-Version: 1.0 References: <20210110124903.109773-1-mailhol.vincent@wanadoo.fr> <20210110124903.109773-2-mailhol.vincent@wanadoo.fr> <20210111171152.GB11715@hoboy.vegasvil.org> In-Reply-To: <20210111171152.GB11715@hoboy.vegasvil.org> From: Vincent MAILHOL Date: Tue, 12 Jan 2021 09:00:33 +0900 Message-ID: Subject: Re: [PATCH v3 1/1] can: dev: add software tx timestamps To: Richard Cochran Cc: Marc Kleine-Budde , linux-can , Jeroen Hofstee , Wolfgang Grandegger , "David S. Miller" , Jakub Kicinski , "open list:NETWORKING DRIVERS" , open list Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue. 12 Jan 2021 at 02:11, Richard Cochran wrote: > > On Sun, Jan 10, 2021 at 09:49:03PM +0900, Vincent Mailhol wrote: > > * The hardware rx timestamp of a local loopback message is the > > hardware tx timestamp. This means that there are no needs to > > implement SOF_TIMESTAMPING_TX_HARDWARE for CAN sockets. > > I can't agree with that statement. The local loopback is a special > "feature" of CAN sockets, and some programs turn it off. Furthermore, > requiring user space to handle CAN sockets differently WRT Tx time > stamps is user-unfriendly. So I would strongly support adding > SOF_TIMESTAMPING_TX_HARDWARE to the CAN layer in the future. > > (This isn't a criticism of the current patch, though.) Fair enough. Implementing SOF_TIMESTAMPING_TX_HARDWARE would result into having the timestamp being duplicated for the loopback frames but allowing existing programs to work as with no modifications is a good enough reason. Out of curiosity, which programs do you use? I guess wireshark but please let me know if you use any other programs (I just use to write a small C program to do the stuff). Mark: do you want me to send a v4 of that patch with above comment removed or can you directly do the change in your testing branch? Yours sincerely, Vincent