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 2F6FC3314DE; Mon, 5 Jan 2026 20:27:16 +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=1767644837; cv=none; b=Dio0XIR0q/0/vFSvZ5Hh7PwcwaZ2G1+vehSQ6yC9nyNVLyS1QxDC/WBEvSVBH/i9Ve1+Mfl3Ba6qdpVGostbhLLjOgbWn5UyvsoJX0PlAkdgHYW+1OSvL/sTijADWrxUX7v9EXMziY3WekPPgjYQRii1J8VPNNoqPLvY0+dZHPo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767644837; c=relaxed/simple; bh=YXz0nmm5+HrBCxqz9vmblcyiqkrmFZDacZ2BnXGn8FA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ifT+teO5uZ4nt7e/LRrR9AHGWJojh+N5LzcBQX8aTPm2xhNJfdVSP1+IeuW6Vz/S+6vWLxDrPD+17ExR5tPB0Lel2Tr6DyeHJBAriWW3Zv8cv/Y1EhahUmg7/GJwryHmMaB1TIV3x1u9Z6e7OJxloB6RUoCXBr/1ueyg9B5DXCc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mY5HXawX; 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="mY5HXawX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9A651C116D0; Mon, 5 Jan 2026 20:27:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1767644836; bh=YXz0nmm5+HrBCxqz9vmblcyiqkrmFZDacZ2BnXGn8FA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=mY5HXawX4szDKq+1Z146LiVr0FgX8aQk9zFrsenGVppMfnkxGKXnW9BW7eSPSyT6h OAxsf0Fqvcsc+0NhPVueO1si7c2+KyS/8mu/MBQsQf5KP87I3eIBDv/PYP0eNAdZpW uEgLWP4udbrrwveryl6q0ZPcv8KzZ/S9fk6neW86UoOI/n2Qyt7nQDdcrFAeU/p6pF vF1t/0KcjXksZ1XqSskfaPJ570B62u966KhrcMn1Pd6G6Fx10I6wIJK20dOSEnZxkX vDg97TTaZDr7nBu6AaXLSINPEYKlKu5/U3wlS9Ge4H25Jrw9dvrR81fkJpO5xzqU9H +N2t2vSxE14ew== Message-ID: Date: Mon, 5 Jan 2026 21:27:11 +0100 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 v2] can: ctucanfd: fix SSP_SRC in cases when bit-rate is higher than 1 MBit. To: Pavel Pisa , linux-can@vger.kernel.org, Marc Kleine-Budde , David Laight , "David S. Miller" , Andrea Daoud , Wolfgang Grandegger , Paolo Abeni , netdev@vger.kernel.org Cc: Jiri Novak , Ondrej Ille References: <20260105111620.16580-1-pisa@fel.cvut.cz> From: Vincent Mailhol Content-Language: en-US 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: <20260105111620.16580-1-pisa@fel.cvut.cz> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Le 05/01/2026 à 12:16, Pavel Pisa a écrit : > From: Ondrej Ille > > The Secondary Sample Point Source field has been > set to an incorrect value by some mistake in the > past > > 0b01 - SSP_SRC_NO_SSP - SSP is not used. > > for data bitrates above 1 MBit/s. The correct/default > value already used for lower bitrates is Where does this 1 MBit/s threshold come from? Is this an empirical value? The check is normally done on the data BRP. For example we had some problems on the mcp251xfd, c.f. commit 5e1663810e11 ("can: mcp251xfd: fix TDC setting for low data bit rates"). Can you use the TDC framework? Not only would you get a correct calculation for when to activate/deactivate TDC, you will also have the netlink reporting (refer to the above commit for an example). > 0b00 - SSP_SRC_MEAS_N_OFFSET - SSP position = TRV_DELAY > (Measured Transmitter delay) + SSP_OFFSET. > > The related configuration register structure is described > in section 3.1.46 SSP_CFG of the CTU CAN FD > IP CORE Datasheet. > > The analysis leading to the proper configuration > is described in section 2.8.3 Secondary sampling point > of the datasheet. > > The change has been tested on AMD/Xilinx Zynq > with the next CTU CN FD IP core versions: > > - 2.6 aka master in the "integration with Zynq-7000 system" test > 6.12.43-rt12+ #1 SMP PREEMPT_RT kernel with CTU CAN FD git > driver (change already included in the driver repo) > - older 2.5 snapshot with mainline kernels with this patch > applied locally in the multiple CAN latency tester nightly runs > 6.18.0-rc4-rt3-dut #1 SMP PREEMPT_RT > 6.19.0-rc3-dut > > The logs, the datasheet and sources are available at > > https://canbus.pages.fel.cvut.cz/ > > Signed-off-by: Ondrej Ille > Signed-off-by: Pavel Pisa Yours sincerely, Vincent Mailhol