Subject: Re: [PATCH net 1/2] Revert "can: m_can: pci: use custom bit timings for Elkhart Lake"

From: Jakub Kicinski <[email-masked]>
Date: Fri, 13 May 2022 10:21:45 -0700

On Fri, 13 May 2022 15:08:18 +0200 Marc Kleine-Budde wrote:
> From: Jarkko Nikula <[email-masked]>
> 
> This reverts commit 0e8ffdf3b86dfd44b651f91b12fcae76c25c453b.
> 
> Commit 0e8ffdf3b86d ("can: m_can: pci: use custom bit timings for
> Elkhart Lake") broke the test case using bitrate switching.
> 
> | ip link set can0 up type can bitrate 500000 dbitrate 4000000 fd on
> | ip link set can1 up type can bitrate 500000 dbitrate 4000000 fd on
> | candump can0 &
> | cangen can1 -I 0x800 -L 64 -e -fb \
> |     -D 11223344deadbeef55667788feedf00daabbccdd44332211 -n 1 -v -v
> 
> Above commit does everything correctly according to the datasheet.
> However datasheet wasn't correct.
> 
> I got confirmation from hardware engineers that the actual CAN
> hardware on Intel Elkhart Lake is based on M_CAN version v3.2.0.
> Datasheet was mirroring values from an another specification which was
> based on earlier M_CAN version leading to wrong bit timings.
> 
> Therefore revert the commit and switch back to common bit timings.
> 
> Fixes: 0e8ffdf3b86d ("can: m_can: pci: use custom bit timings for Elkhart Lake")
> Link: https://lore.kernel.org/all/[email-masked]
> Signed-off-by: Jarkko Nikula <[email-masked]>
> Reported-by: Chee Hou Ong <[email-masked]>
> Reported-by: Aman Kumar <[email-masked]>
> Reported-by: Pallavi Kumari <[email-masked]>
> Cc: <[email-masked]> # v5.16+
> Signed-off-by: Marc Kleine-Budde <[email-masked]>

nit: the hash in the fixes tag should be:

Fixes: ea4c1787685d ("can: m_can: pci: use custom bit timings for Elkhart Lake")

Do you want to respin or is the can tree non-rebasable?