netdev - Re: ctucanfd: possible coding error in ctucan_set_secondary_sample

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Message-ID: <20251222-kickass-oyster-of-sorcery-c39bb7-mkl@pengutronix.de>
Date: Mon, 22 Dec 2025 17:20:49 +0100
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: Ondrej Ille <ondrej.ille@...il.com>
Cc: Andrea Daoud <andreadaoud6@...il.com>, 
	Pavel Pisa <pisa@....felk.cvut.cz>, linux-can@...r.kernel.org, 
	Wolfgang Grandegger <wg@...ndegger.com>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Christophe JAILLET <christophe.jaillet@...adoo.fr>, 
	netdev@...r.kernel.org
Subject: Re: ctucanfd: possible coding error in
 ctucan_set_secondary_sample_point causing SSP not enabled

On 22.12.2025 16:51:07, Ondrej Ille wrote:
> yes, your thinking is correct, there is a bug there.
>
> This was pointed to by another user right in the CTU CAN FD repository
> where the Linux driver also lives:
> https://github.com/Blebowski/CTU-CAN-FD/pull/2
>
> It is as you say, it should be:
>
> -- ssp_cfg |= FIELD_PREP(REG_TRV_DELAY_SSP_SRC, 0x1);
> ++ ssp_cfg |= FIELD_PREP(REG_TRV_DELAY_SSP_SRC, 0x0);

This statement has no effect, as 'ssp_cfg |= 0x0' is still 'ssp_cfg'.
IMHO it's better to add a comment that says, why you don't set
REG_TRV_DELAY_SSP_SRC. Another option is to add create a define that
replaces 0x1 and 0x0 for REG_TRV_DELAY_SSP_SRC with a speaking name.

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
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