Received-SPF: pass (google.com: domain of linux-kernel+bounces-74885-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Date: Wed, 21 Feb 2024 15:24:24 +0100
From: Marc Kleine-Budde <mkl@pengutronix.de>
To: Oliver Hartkopp <socketcan@hartkopp.net>
Cc: Vincent MAILHOL <mailhol.vincent@wanadoo.fr>, 
	Maxime Jayat <maxime.jayat@mobile-devices.fr>, Wolfgang Grandegger <wg@grandegger.com>, 
	linux-can@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] can: netlink: Fix TDCO calculation using the old data
 bittiming
Message-ID: <20240221-garden-petted-789304a1b1a5-mkl@pengutronix.de>
References: <40579c18-63c0-43a4-8d4c-f3a6c1c0b417@munic.io>
 <CAMZ6Rq+10m=yQ9Cc9gZQegwD=6iCU=s1r78+ogJ4PV0f5_s+tQ@mail.gmail.com>
 <54afa5e8-fb5e-4d90-8897-8f3c5a684418@hartkopp.net>
Precedence: bulk
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
	protocol="application/pgp-signature"; boundary="inlfg5asntdkuyns"
Content-Disposition: inline
In-Reply-To: <54afa5e8-fb5e-4d90-8897-8f3c5a684418@hartkopp.net>


--inlfg5asntdkuyns
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On 21.02.2024 15:14:02, Oliver Hartkopp wrote:
> I have an old PCAN USB adapter (Classical CAN) which uses the pcan_usb
> driver and wanted to set a 50kbit/s bitrate:
>=20
> ip link set can0 up txqueuelen 500 type can bitrate 50000 sjw 4
>=20
> First it complained about the SJW having a higher value than some phase-s=
eg
> value which was 2.
>=20
> Error: sjw: 4 greater than phase-seg2: 2.
>=20
> I always thought the driver automatically adapts the SJW value to the
> highest possible and SJW=3D4 could always be set. Did this change at a ce=
rtain
> point?

Yes, that changed with b5a3d0864ee7 ("can: bittiming: can_sjw_check():
check that SJW is not longer than either Phase Buffer Segment")

See discussion in https://lore.kernel.org/all/20220907103845.3929288-3-mkl@=
pengutronix.de/

> Anyway, then I reduced the given SJW value and the ip command did not give
> any error message.
>=20
> But finally there was not CAN traffic possible with my "always working
> setup".
>=20
> I'm running 6.8.0-rc4-00433-g92a355464776 from Linus' tree.
>=20
> Reverting this patch fixed my issue.

But what has the tdco calculation to do with non CAN-FD controllers?

Marc

--=20
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung N=C3=BCrnberg              | Phone: +49-5121-206917-129 |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |

--inlfg5asntdkuyns
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----

iQEzBAABCgAdFiEEUEC6huC2BN0pvD5fKDiiPnotvG8FAmXWB5UACgkQKDiiPnot
vG8Sogf9GDTH+r+dpvL4+IwbOEdFwI4awCIUJ/mrGD+zql/rNCPxYWz6liDuKOJk
DnXqOSuPPBoDorLLWf58H/1pgwCu4Lo+TaJ9x1igrKpt0lFxBJ7a7FO0tcjFeE2N
jjlSukRzehY2Iqo4oL+y3ZdwQoeqFFCj/dNVISpZWDGDA3YieAyVQ2lsbd6TJVb1
Ft5eKJzNNNfuh+8uGkPQ0j9QYu7ptyTZorAKiZy5ucJYl+sRd22vXU2crIIByBtK
YuRclqXEm1aG45kQmNZB9tJsnXxFZHcFXdhnmxtrwpi23S67Fbk0DPPW0+U5mpW3
6g/I9/+HvqmGm5L1CKz+3PKQ7Wjt3g==
=7CLS
-----END PGP SIGNATURE-----

--inlfg5asntdkuyns--