Re: [PATCH v3] watchdog: sp5100_tco: allow unreserved MMIO on GA-78LMT-USB3

[Guenter Roeck]

On Fri, Aug 21, 2026 at 04:25:11PM +0200, Christoph Berliner wrote:
> The Gigabyte GA-78LMT-USB3 firmware programs the legacy SP5100
> watchdog MMIO window at 0xfec000f0. This address falls inside the
> IOAPIC resource, so sp5100_tco fails to reserve it and aborts probing.
> 
> Do not relocate or reprogram the watchdog. Instead, add a narrowly
> scoped DMI quirk for this board which permits use of the
> firmware-provided MMIO address without reserving it.
> 
> The exception is limited to the legacy SP5100 register layout, the
> GA-78LMT-USB3 DMI identity, and the firmware address 0xfec000f0.
> All other systems retain the existing resource reservation behavior.
> 
> On the affected system the watchdog initializes successfully and
> /dev/watchdog0 is registered while the firmware-programmed watchdog
> base remains unchanged at 0xfec000f0 during load and unload.
> 
> Tested on a Gigabyte GA-78LMT-USB3 with AMD SBx00 SMBus controller
> (PCI 1002:4385, revision 0x3c).
> 
> Signed-off-by: Christoph Berliner <caberliner@xxxxxxxxx>

Applied.

Thanks,
Guenter