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 24E7D2FE594; Mon, 13 Oct 2025 10:12:09 +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=1760350331; cv=none; b=eGwAjg6c1u4cc7Wx3/vY5hqPjSyjHTXJREO/QMxGZ+6/KZBguQAkJTaNbYIeUy6smZjQnRvwjB73u3C4l9X2jlPkodMGiAZDck8Z89qiSOlbebyDYHBiDR4HSoU7tmp1MsSUS7YtDB92xNrRxaOOM7TS3imHsEl+jnB1gV9uYXg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760350331; c=relaxed/simple; bh=D685IFTElATHf+I2pgbQcF/yZIN1IETUvG4g5c+YtJs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Gyj4EK3QadZ9DF3DidX3qwS8G7arP8pzTk8GXP/VxuY6HVEmhN1UUbxQ5fII71wM+lW4wczyQdpdvVS1XRNkUPZFgdGXRbb/OKU34ysdXZU63E0YqKU7Wl/IORcSFdODeHltPbZInhxdNPb8Svb3+FpVuIvMvni3oqlGdaKJEnY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JbUHPfOg; 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="JbUHPfOg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 17A2BC4CEFE; Mon, 13 Oct 2025 10:12:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1760350329; bh=D685IFTElATHf+I2pgbQcF/yZIN1IETUvG4g5c+YtJs=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=JbUHPfOgDslajzzcY8/CZ1qXoIzIr7a1cQo+iC3FSXT2uNMgYIDhJR28R88RoS/If CUkLPXmA5ls0RvaLzI1pz3vmKckVFbfHnALIqkRDXOCOGo/pAqJa0Tl2ONpb7cmvcB J28M4IA4Y5eUQVThgm7nlg/EHQKlSFPYXjRd49mu+z/lIjbqMmoM7Mnj2GRDHJYLZ8 jNYQSsAiRFDU2qCWUzP3MRYVSh3ukrQW0XJu1FbkkkVFRt1wgFU20wWbKTT0rczlZN ySN/pUVgHtSy0pgYiZZYPMCynS8HiXj8X6eFaxA01mi/hwyDhw+o8QDFbYWqxM+JJh wTCbNVESxu9tA== Message-ID: <60348755-be5e-4e64-82e7-98178ca73623@kernel.org> Date: Mon, 13 Oct 2025 19:12:06 +0900 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net 9/9] can: add Transmitter Delay Compensation (TDC) documentation To: Paolo Abeni , Simon Horman Cc: davem@davemloft.net, kuba@kernel.org, linux-can@vger.kernel.org, kernel@pengutronix.de, Marc Kleine-Budde , netdev@vger.kernel.org References: <20251012142836.285370-1-mkl@pengutronix.de> <20251012142836.285370-10-mkl@pengutronix.de> <1157f3fe-f88b-449f-a4c2-aac9d27c95ea@redhat.com> 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: <1157f3fe-f88b-449f-a4c2-aac9d27c95ea@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Paolo and Simon, Sorry for the build error. (for the record, Simon separately reported the same issue here: https://lore.kernel.org/linux-can/aOzJZ1NsKxNMvIzJ@horms.kernel.org/) On 13/10/2025 at 16:45, Paolo Abeni wrote: > Ni, > > On 10/12/25 4:20 PM, Marc Kleine-Budde wrote: >> From: Vincent Mailhol >> >> Back in 2021, support for CAN TDC was added to the kernel in series [1] >> and in iproute2 in series [2]. However, the documentation was never >> updated. >> >> Add a new sub-section under CAN-FD driver support to document how to >> configure the TDC using the "ip tool". >> >> [1] add the netlink interface for CAN-FD Transmitter Delay Compensation (TDC) >> Link: https://lore.kernel.org/all/20210918095637.20108-1-mailhol.vincent@wanadoo.fr/ >> >> [2] iplink_can: cleaning, fixes and adding TDC support >> Link: https://lore.kernel.org/all/20211103164428.692722-1-mailhol.vincent@wanadoo.fr/ >> >> Signed-off-by: Vincent Mailhol >> Link: https://patch.msgid.link/20251012-can-fd-doc-v1-2-86cc7d130026@kernel.org >> Signed-off-by: Marc Kleine-Budde >> --- >> Documentation/networking/can.rst | 60 ++++++++++++++++++++++++++++++++ >> 1 file changed, 60 insertions(+) >> >> diff --git a/Documentation/networking/can.rst b/Documentation/networking/can.rst >> index ccd321d29a8a..402fefae0c2f 100644 >> --- a/Documentation/networking/can.rst >> +++ b/Documentation/networking/can.rst >> @@ -1464,6 +1464,66 @@ Example when 'fd-non-iso on' is added on this switchable CAN FD adapter:: >> can state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0 >> >> >> +Transmitter Delay Compensation >> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> + >> +At high bit rates, the propagation delay from the TX pin to the RX pin of >> +the transceiver might become greater than the actual bit time causing >> +measurement errors: the RX pin would still be measuring the previous bit. >> + >> +The Transmitter Delay Compensation (thereafter, TDC) resolves this problem >> +by introducing a Secondary Sample Point (SSP) equal to the distance, in >> +minimum time quantum, from the start of the bit time on the TX pin to the >> +actual measurement on the RX pin. The SSP is calculated as the sum of two >> +configurable values: the TDC Value (TDCV) and the TDC offset (TDCO). >> + >> +TDC, if supported by the device, can be configured together with CAN-FD >> +using the ip tool's "tdc-mode" argument as follow:: ^ This is the culprit. There should have been as single colon here... >> + >> +- **omitted**: when no "tdc-mode" option is provided, the kernel will >> + automatically decide whether TDC should be turned on, in which case it > > The above apparently makes htmldoc unhappy: > > New errors added > --- /tmp/tmp.ZsYbmUst3Y 2025-10-12 14:23:45.746737362 -0700 > +++ /tmp/tmp.8o1xOCQtDp 2025-10-12 14:58:29.920405220 -0700 > @@ -15,0 +16 @@ > +/home/doc-build/testing/Documentation/networking/can.rst:1484: ERROR: > Unexpected indentation. > > Could you please address the above and send a v2? Here it is: https://lore.kernel.org/r/20251013-can-fd-doc-v2-0-5d53bdc8f2ad@kernel.org Yours sincerely, Vincent Mailhol