Odd ada(4) failures when trying using USB scanner

Hi,
I'm using -current as of r202157.

When attaching an epson USB scanner and trying to `scanimage -L`
I get a freeze for some time and the following console logs:
...
ata1: FAILURE - odd-sized DMA transfer attempt 5 % 2
ata1: setting up DMA failed
ata1: FAILURE - odd-sized DMA transfer attempt 5 % 2
ata1: setting up DMA failed
ata1: FAILURE - odd-sized DMA transfer attempt 5 % 2
ata1: setting up DMA failed
ata1: FAILURE - odd-sized DMA transfer attempt 5 % 2
ata1: setting up DMA failed
ahcich1: Timeout on slot 19
ahcich1: is 04000000 cs 00080000 ss 00080000 rs 00080000 tfd 451 serr 00400000
ahcich2: Timeout on slot 20
ahcich2: is 04000000 cs 00100000 ss 00100000 rs 00100000 tfd 451 serr 00400000
ahcich3: Timeout on slot 18
ahcich3: is 04000000 cs 00040000 ss 00000000 rs 00040000 tfd 451 serr 00400000
ahcich3: Timeout on slot 18
ahcich3: is 00000000 cs 00040000 ss 00000000 rs 00040000 tfd c0 serr 00000001
ugen2.2: <EPSON> at usbus2 (disconnected)
ahcich2: Timeout on slot 20
ahcich2: is 00000000 cs 00300000 ss 00000000 rs 00300000 tfd c0 serr 00000001
ahcich0: Timeout on slot 24
ahcich0: is 04000000 cs 01000000 ss 01000000 rs 01000000 tfd 451 serr 00400000
mfi0: 32975 (318240776s/0x0008/info) - Battery charge complete
ahcich0: Timeout on slot 24
ahcich0: is 00000000 cs 01000000 ss 00000000 rs 01000000 tfd c0 serr 00000001
...

After the timeouts the system is usable again.

It seems the new ATA-CAM subsystem doesn't like the CAM or USB scanning 
for known scanners.

Any clues how to fix?

Thanks id advance!

Bye/2
---
Michael Reifenberger
Michael_at_Reifenberger.com
http://www.Reifenberger.com