From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 958C12FB615 for ; Mon, 10 Nov 2025 21:22:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762809734; cv=none; b=uEAe31zSI6cBYpeiRM7S5hGUeZDpMtpEBMt29BDhtm/RJB66qhC2H2FfittoDrYrNvXHW2MHOUkJftexsDiz1jf2dra9TMUZHVeBTOErYovmVTESWJK0emEBNPirvwlOpr0uYb0Jx+NGYwIY5w8y3lFJoBJOrJYwtvot1i/oNbM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762809734; c=relaxed/simple; bh=TjUk/iSpI+JlIT2AKZ97h63PVCpcy30d/iT/6PcXoEA=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=Tx6pBk2TW6l6R3sfezrWaUJbM7mc0Tg9jIAT1CN53Deyb77HbvJ5/7F2MSCwRiz4+gjKB7lNt6zjL0XgBcUxT/PhAzEopnC0bZ/hhFW202AppNl6LZf5tN6JCWBkBwLUFXSaXF9dL4sxzX1ITp8pRbES7zUUCa2bZz78EuoC5Rs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dLSaBVAd; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dLSaBVAd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 99130C2BC86; Mon, 10 Nov 2025 21:22:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762809734; bh=TjUk/iSpI+JlIT2AKZ97h63PVCpcy30d/iT/6PcXoEA=; h=Date:Subject:To:References:From:In-Reply-To:From; b=dLSaBVAdd/v4VCkmEM71WwYD3/mXUs5afTWTE8SQ13RnxX8AJOFzz0ZfkyvttZZaj HLC4pxJ+7ptVpu7VTp37cpOdcEoNFtdheLQSoc9ALsnHfEHITtXltaa7Os6RlR94Rc FjPIqS56C7s0BKg4pcIxf4/8XGN6kvcM49NklPCIwvpyfKZHMMU/6N0c1zCKl/bkOP XFr7iIzwmg8hNUvgc3JeyzydJfxOGVi9qEuvdrYMtj+Trx9FZysCC/K0WYNxUregre PtG4YH9iEG9R8ahH9ZUoaMJXVk0tBBNOEIOXg1HU+Ymdvp/7rD6kZi7plKzmjkLlO9 jRmS4iOmn2X+g== Message-ID: Date: Mon, 10 Nov 2025 22:22:11 +0100 Precedence: bulk X-Mailing-List: linux-can@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: RFC remove CAN_CTRLMODE_XL_ERR_SIGNAL To: Oliver Hartkopp , linux-can@vger.kernel.org References: <84cb473f-be5b-464b-a5d9-10c6f643f145@hartkopp.net> Content-Language: en-US From: Vincent Mailhol Autocrypt: addr=mailhol@kernel.org; keydata= xjMEZluomRYJKwYBBAHaRw8BAQdAf+/PnQvy9LCWNSJLbhc+AOUsR2cNVonvxhDk/KcW7FvN JFZpbmNlbnQgTWFpbGhvbCA8bWFpbGhvbEBrZXJuZWwub3JnPsKZBBMWCgBBFiEE7Y9wBXTm fyDldOjiq1/riG27mcIFAmdfB/kCGwMFCQp/CJcFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcC F4AACgkQq1/riG27mcKBHgEAygbvORJOfMHGlq5lQhZkDnaUXbpZhxirxkAHwTypHr4A/joI 2wLjgTCm5I2Z3zB8hqJu+OeFPXZFWGTuk0e2wT4JzjgEZx4y8xIKKwYBBAGXVQEFAQEHQJrb YZzu0JG5w8gxE6EtQe6LmxKMqP6EyR33sA+BR9pLAwEIB8J+BBgWCgAmFiEE7Y9wBXTmfyDl dOjiq1/riG27mcIFAmceMvMCGwwFCQPCZwAACgkQq1/riG27mcJU7QEA+LmpFhfQ1aij/L8V zsZwr/S44HCzcz5+jkxnVVQ5LZ4BANOCpYEY+CYrld5XZvM8h2EntNnzxHHuhjfDOQ3MAkEK In-Reply-To: <84cb473f-be5b-464b-a5d9-10c6f643f145@hartkopp.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Oliver, On 09/11/2025 at 22:07, Oliver Hartkopp wrote: > Hi Vincent, > > I've been playing with the PEAK CAN XL bitrate tool again and it gave me a new > idea: > > There were settings for different bitrates and the belonging/resulting flags for > TMS and ES (error-signalling). > > Staring at the options we have only three options for the CAN XL support aka "xl > on": > > 1. Providing CC/FD/XL bitrates => ES on, TMS off (mixed-mode) > > 2. Providing only CC/XL bitrates => ES off, TMS off (CANXL-only) > > 3. Providing only CC/XL bitrates => ES off, TMS on (CANXL-only) Why isn't 4. Providing only CC/XL bitrates => ES on, TMS off a valid option? > Therefore we only need "tms" as an additional option when xl is on. > > The error signalling "on" automatically results from the availability of "fd on" > and the FD bitrate. > > Examples: > > 1. Providing CC/FD/XL bitrates => ES on, TMS off > > ip link set can0 type can bitrate 500000 fd on dbitrate 2000000 xl on xbitrate > 4000000 > > 2. Providing only CC/XL bitrates => ES off, TMS off > > ip link set can0 type can bitrate 500000 xl on xbitrate 4000000 > > 3. Providing only CC/XL bitrates => ES off, TMS on > > ip link set can0 type can bitrate 500000 xl on xbitrate 10000000 tms on > > That's simple and provides only the needed switches, which makes > CAN_CTRLMODE_XL_ERR_SIGNAL obsolete in the netlink API. > > What do you think about this approach? What really bothers me here is that the ISO standard explicitly state that error signaling is a configurable option. Making this an implicit option would result in a somehow non-compliant implementation. I appreciate that for most of the use cases the error signaling can be inferred from the other values, and this is what I tried to implement (c.f. the table of default values which I put in my patch). But I want to leave room so that people who wants to push the standard to its limits can. I see this a bit like the can_frame->len8_dlc thing. Should you use DLCs greater than 8 in production code? Hell no! But I still want the implementation to give me this option so that I can do my weird tests. Yours sincerely, Vincent Mailhol