From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpfb2-g21.free.fr (smtpfb2-g21.free.fr [212.27.42.10]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 5B36F33556C; Mon, 17 Nov 2025 13:37:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=212.27.42.10 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763386656; cv=none; b=Y6DVeP5OAv/H+e1YyKLrS/Ham7pFqgfCZ83qDB9s84u5QSifgxzGB+ayV4mjubTNDEfNtdN7DeiREgcuu6Lv6RmttOFFcDd/HQovtoXbftPTljMD5b8v7cbuhtYO2UB6bxhV+RkxiGVsqFkDax+ccwQ1yu3oYlqJXsxJJJBjlNk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763386656; c=relaxed/simple; bh=xED8t/egsDUASzU6YzpvEL9qdEDzrwbPuclwRLvS2L0=; h=Date:From:To:Cc:Message-ID:In-Reply-To:Subject:MIME-Version: Content-Type; b=fIlLGLYU8wPN3H5L91nbipIaqjXfChr+x6R6LiHL6u/8HHGyHBREZFQSkpu+d4grsmwj7vObgN3+EmUbBSowAUnlv6cDZAz2mvYV0wNWvE0N9ugA0Xj0xBt+Hw/Ep1ronu9aKaSMKdsCEVx+yRRCskx6QtxIm1zXawn0LwHl0FE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=free.fr; spf=pass smtp.mailfrom=free.fr; dkim=pass (2048-bit key) header.d=free.fr header.i=@free.fr header.b=fM71aA9X; arc=none smtp.client-ip=212.27.42.10 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=free.fr Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=free.fr Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=free.fr header.i=@free.fr header.b="fM71aA9X" Received: from smtp1-g21.free.fr (smtp1-g21.free.fr [212.27.42.1]) by smtpfb2-g21.free.fr (Postfix) with ESMTP id CFE344D005; Mon, 17 Nov 2025 14:31:45 +0100 (CET) Received: from zimbra65-e11.priv.proxad.net (unknown [172.20.243.215]) by smtp1-g21.free.fr (Postfix) with ESMTP id 4BB38B0054E; Mon, 17 Nov 2025 14:31:38 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=free.fr; s=smtp-20201208; t=1763386298; bh=xED8t/egsDUASzU6YzpvEL9qdEDzrwbPuclwRLvS2L0=; h=Date:From:To:Cc:In-Reply-To:Subject:From; b=fM71aA9XpnYdxnQ6iIkKzmQfisTFy937P3O9gje3zQ4Svpir3noZCinx3NRLzmdJK xfgyzbn1Fvt2hSYVC3iLpwvSkdmo/t/96IVnhnPwg3/WH2oXWfY+PO/Bnzd8Yin0lb 9FUuLiicUaB209sNwHZWDy2ZBDr5wcbuUJzTqMvfyoskfOMvs/45+Zc0Ubrgbcyc/0 SmHucygKU95sorsRnpn9iFtbt8ZSXTZDllWvQ+2MShVyHy+FdYNldBiaqwqE1iApYC 6pbbYgx8NG9p2BXAZf3ue/UiRFy+Sla+g1pj/VZSrduAKis4lsBlH/107RnyiFtpc/ aFihVi0A+9KXw== Date: Mon, 17 Nov 2025 14:31:38 +0100 (CET) From: =?utf-8?Q?St=C3=A9phane?= Grosjean To: Vincent Mailhol Cc: =?utf-8?Q?St=C3=A9phane?= Grosjean , Robert Nawrath , Minh Le , Duy Nguyen , linux-can@vger.kernel.org, linux-kernel@vger.kernel.org, Oliver Hartkopp , Marc Kleine-Budde Message-ID: <2145685673.654764160.1763386298170.JavaMail.root@zimbra65-e11.priv.proxad.net> In-Reply-To: <72d2721c-6713-4e6a-b0d4-28f600715808@kernel.org> Subject: Re: [PATCH 3/9] can: netlink: add initial CAN XL support Precedence: bulk X-Mailing-List: linux-can@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Mailer: Zimbra 7.2.0-GA2598 (ZimbraWebClient - GC142 (Linux)/7.2.0-GA2598) X-Authenticated-User: stephane.grosjean@free.fr Hi Vincent, > Then, should we go for this or not? The benefit I see to add this > check would be > less effort on the patch reviews for new devices (which I am mostly > doing > recently). I can foreseen that people will wrongly use > CAN_CTRLMODE_LISTENONLY > instead of CAN_CTRLMODE_RESTRICTED. This piece of code will make sure > that they > will implement CAN_CTRLMODE_RESTRICTED. And because this feature is > mandatory, I > thought this wasn't a too bad idea. This will also save me the effort > to ask if > to people submitting patches if this feature is supported or not. I understand the benefits for you. But I see the disadvantages for the user= . Regardless of whether RESTRICTED mode is mandatory, not requesting this m= ode should not result in what looks like an error message for the user. As = it stands, the fact that it is even a warning is even more confusing, since= the interface is configured anyway. And I don't think I'm an average user.= Given that the interface will be configured anyway, this warning is more d= isruptive than useful to me. And that's really a strong opinion. =20 > If someone comes with a non-compliant device, we can still statically > set the > flag. So this isn't even a blocker for non compliant devices. >=20 After reading the very strict interpretation of the ES bit (which I also ag= ree with, despite being the originator of the initial simplification propos= al), I admit that I don't understand this: Speaking of my case: our CANXL core does not currently include RESTRICTED m= ode (which is considered more of an option to be added in the future). If C= ANXL grows in popularity, it will be much more due to its finally relevant = throughputs and payload length than to this mode, which is close to LISTEN_= ONLY in my opinion. Furthermore, I find it hard to imagine that the RESTRICTED flag would be ad= ded statically, whereas in reality, considering it as an option, the driver= could add it as a feature finally supported by new firmware versions. I see it more like CAN_CTRLMODE_CC_LEN8_DLC: if I'm not mistaken, DLC value= s > 8 have always been allowed by the standard, and yet it was only added i= n 5.11. At worst, let's define a flag such as CAN_CTRLMODE_FD_NON_ISO, i.e., CAN_CT= RLMODE_XL_NON_RESTRICTED. > So, at the end, this is mostly a selfish feature to remove some patch > reviewing > effort (while still pushing toward ISO compliance, which isn't a bad > thing either). >=20 > I prefer to have it like this, but this isn't a strong opinion > either. >=20 >=20 > Yours sincerely, > Vincent Mailhol >=20 Looking forward to hearing from you, -- St=C3=A9phane=20