Re: [PATCH] can: j1939: fix wrong rx timeout for CTS hold messages

[Oleksij Rempel <o.rempel@pengutronix.de>]

Hi Alexander,

On Tue, Apr 21, 2026 at 05:31:54PM +0200, Alexander Hölzl wrote:
> In J1939 segmented transport, a CTS message with data byte 2 set to zero is interpreted as a hold message.
> This instructs the transmitter of the segmented message to hold the connection open but to delay sending.
> According to the J1939-21 standard, section 5.10.2.4 the timeout T4 after which an held open session is invalidated is
> 1050 ms, not 550 as implemented currently.
> The 550 ms are problematic if a device uses hold messages and assumes it can wait for more than 550 ms before it has
> to resend the hold message.
> 
> This patch changes the T4 timeout used in the implementation from 550 ms to 1050.
> 
> Signed-off-by: Alexander Hölzl <alexander.hoelzl@gmx.net>

LGTM. Thank you!

Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>


Sashico detected one more potential issue, not related to this patch:
https://sashiko.dev/#/patchset/20260421153152.87772-3-alexander.hoelzl%40gmx.net

If you have time, can you please verify it?

Best Regards,
Oleksij
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