netdev - Re: [RFC PATCH v3 8/9] can: slcan: add support to set bit time register (btr)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:   Sun, 31 Jul 2022 20:58:03 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Dario Binacchi <dario.binacchi@...rulasolutions.com>
Cc:     Max Staudt <max@...as.org>, linux-kernel@...r.kernel.org,
        linux-can@...r.kernel.org,
        Oliver Hartkopp <socketcan@...tkopp.net>,
        michael@...rulasolutions.com,
        Amarula patchwork <linux-amarula@...rulasolutions.com>,
        Jeroen Hofstee <jhofstee@...tronenergy.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Wolfgang Grandegger <wg@...ndegger.com>, netdev@...r.kernel.org
Subject: Re: [RFC PATCH v3 8/9] can: slcan: add support to set bit time
 register (btr)

On 31.07.2022 17:54:01, Dario Binacchi wrote:
> > If an adapter follows 100% the official firmware doc the BTR registers
> > are interpreted as SJA1000 with 8 MHz CAN clock.
> 
> I checked the sources and documentation of the usb adapter I used (i.
> e. Https://www.fischl.de/usbtin/):
> ...
> sxxyyzz[CR]                 Set can bitrate registers of MCP2515. You
> can set non-standard baudrates which are not supported by the "Sx"
> command.

I hope the effective clock speed is documented somewhere, as you need
this information to set the registers.

>                                      xx: CNF1 as hexadecimal value (00-FF)
>                                      yy: CNF2 as hexadecimal value (00-FF)
>                                      zz: CNF3 as hexadecimal value
> ...
> 
> Different from what is reported by can232_ver3_Manual.pdf :
> 
> sxxyy[CR]         Setup with BTR0/BTR1 CAN bit-rates where xx and yy is a hex
>                          value. This command is only active if the CAN
> 
> And here is the type of control carried out by the slcan_attach for
> the btr parameter:
> https://github.com/linux-can/can-utils/blob/master/slcan_attach.c#L144
> When I would have expected a different check (i. e. if (strlen(btr) > 4).
> Therefore it is possible that each adapter uses these bytes in its own
> way as well as
> in the content and also in the number of bytes.

I expected something like that.

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |

Download attachment "signature.asc" of type "application/pgp-signature" (489 bytes)