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

From: Marc Kleine-Budde

Date: Wed Oct 14 2026 - 19:06:58 EST


> 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@xxxxxxx>

Is this patch still relevant?

regards,
Marc

--
Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>