Re: [PATCH v4 4/7] can: rcar_canfd: Do not set registers selecting the CAN mode

[Claudiu Beznea <claudiu.beznea+renesas@tuxon.dev>]

On 9/2/26 17:29, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
> 
> New issues:
> - [High] Software state diverges from fixed hardware capabilities due to unvalidated device tree overrides, causing silent data corruption and CAN protocol violations.
> 
> Pre-existing issues:
> - [High] Race condition on write-0-to-clear status register causes lost TX completion interrupts and permanently frozen TX queues.
> --
> 
> commit f5c5dd93cfcd4bdec86a8b0c4bc20cba21d7f4dc
> Author: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> 
> can: rcar_canfd: Do not set registers selecting the CAN mode
> 
> This commit adds a fixed_canfd flag to struct rcar_canfd_hw_info to handle
> hardware like the Renesas RZ/G3S SoC that only supports CAN-FD mode. It skips
> writing to unavailable CAN mode configuration bits during the reset controller
> sequence.
> 
> Link: https://lore.kernel.org/all/1d9719e3-10ff-4cd8-b729-55fea93c37ce@wanadoo.fr
> 
>> diff --git a/drivers/net/can/rcar/rcar_canfd.c b/drivers/net/can/rcar/rcar_canfd.c
>> index 2e84dc5dfa34d..bed7cde1aa01b 100644
>> --- a/drivers/net/can/rcar/rcar_canfd.c
>> +++ b/drivers/net/can/rcar/rcar_canfd.c
> 
> [ ... ]
> 
>> @@ -846,6 +852,9 @@ static int rcar_canfd_reset_controller(struct rcar_canfd_global *gpriv)
>>   		}
>>   
>>   		/* Set the controller into appropriate mode */
>> +		if (gpriv->info->fixed_canfd)
>> +			continue;
>> +
> 
> [Severity: High]
> Does bypassing the hardware mode setup here create a state mismatch if
> the software interface is forced into Classical CAN mode?
> 
> If the device tree contains the "renesas,no-can-fd" property, the probe
> function sets fdmode = false in rcar_canfd_probe():

It is the same thing here. The "renesas-no-can-fd" was forbidden for RZ/G3S.