Re: Hitting WARN_ON_ONCE in i2c-designware-common.c

[Jesper Dangaard Brouer <hawk@kernel.org>]

On 15/04/2025 14.28, Jarkko Nikula wrote:
> Hi
> 
> On 4/15/25 3:03 PM, Jesper Dangaard Brouer wrote:
>> Hi Maintainers,
>>
>> I'm hitting a WARN_ON_ONCE in drivers/i2c/busses/i2c-designware-common.c
>> when booting the kernel on our Gen12 hardware.
>>
>> I'm using devel kernel net-next at commit 1a9239bb425 (merge tag 'net- 
>> next-6.15').
>>
> Is this a regression so was this working before?
> 

I'm seeing this when doing kernel development and booting net-next on
our Gen12 servers[1].  [1] https://blog.cloudflare.com/gen-12-servers/

I've not seen this WARN on our production kernels (stable 6.6 and 6.12).
This is likely due to different kernel configs.

> Support for this platform was added back in 2016 by the commit 
> e4e666ba74d4 ("i2c: designware: Add device HID for future AMD I2C 
> controller").
> 

Maybe we have just not enabled the module on our prod kernels.

>> [   10.062651] i2c_designware AMDI0010:00: Unknown Synopsys component type: 0xffffffff
>> [   10.073312] pps_core: LinuxPPS API ver. 1 registered
>> [   10.073372] piix4_smbus 0000:00:14.0: SMBus Host Controller at 0xb00, revision 0
>> [   10.075433] i2c_designware AMDI0010:01: Unknown Synopsys component type: 0xffffffff
> 
> These "Unknown Synopsys component type: 0xffffffff" errors indicate IP 
> is not alive. Perhaps linked to the missing clock or not powered.

It is possible that this hardware is special as I believe it is 
customized for us.

The dmesg output also contained:
  Hardware name: Lenovo HR355M-V3-G12/HR355M_V3_HPM
(see the extra -G12 to the SKU.)

--Jesper