ahcisata and WDCTL_RST

[John Klos <john%ziaspace.com@localhost>]

Hi,

I have an older MSi MS-7511 motherboard (it just happens to be the one 
that the NetBSD Foundation gave to certain developers). It has run fine 
for years, but with NetBSD-7 and -current, ahcisata will only recognize 
SATA drives every tenth boot or so. There's no discernible pattern:

ahcisata0 at pci0 dev 9 function 0: vendor 0x10de product 0x0ad0 (rev. 0xa2)
LSA0: Picked IRQ 21 with weight 1
ahcisata0: interrupting at ioapic0 pin 21
ahcisata0: 64-bit DMA
ahcisata0: ignoring broken port multiplier support
ahcisata0: AHCI revision 1.20, 6 ports, 32 slots, CAP 0xe3209f05<PMD,ISS=0x2=Gen2,SCLO,SAL,SSNTF,SNCQ,S64A>
atabus0 at ahcisata0 channel 0
atabus1 at ahcisata0 channel 1
atabus2 at ahcisata0 channel 2
atabus3 at ahcisata0 channel 3
atabus4 at ahcisata0 channel 4
atabus5 at ahcisata0 channel 5
...
ahcisata0 port 1: device present, speed: 3.0Gb/s
ahcisata0 port 2: device present, speed: 3.0Gb/s
ahcisata0 port 0: device present, speed: 3.0Gb/s
ahcisata0 port 3: device present, speed: 3.0Gb/s
ahcisata0 channel 0: clearing WDCTL_RST failed for drive 0
ahcisata0 channel 1: clearing WDCTL_RST failed for drive 0
ahcisata0 channel 2: clearing WDCTL_RST failed for drive 0
ahcisata0 channel 3: clearing WDCTL_RST failed for drive 0


With NetBSD 7.0.1 installation kernel, I get the same as above but:

ahcisata0 port 3: device present, speed: 3.0Gb/s
ahcisata0 port 1: device present, speed: 3.0Gb/s
ahcisata0 port 2: device present, speed: 3.0Gb/s
ahcisata0 port 0: device present, speed: 3.0Gb/s
atabus0: Unrecognized signature 0x00000001 on port 0. Assuming it's a disk.
atabus3: Unrecognized signature 0x00000001 on port 0. Assuming it's a disk.
atabus2: Unrecognized signature 0x00000001 on port 0. Assuming it's a disk.
atabus1: Unrecognized signature 0x00000001 on port 0. Assuming it's a disk.
wd0 at atabus0 drive 0
wd0: <SanDisk SDSSDH120GG25>
wd0: drive supports 16-sector PIO transfers, LBA48 addressing
wd0: 111 GB, 232581 cyl, 16 head, 63 sec, 512 bytes/sect x 234441648 sectors
wd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 6 (Ultra/133)
wd0(ahcisata0:0:0): using PIO mode 4, DMA mode 2, Ultra-DMA mode 6 (Ultra/133) (using DMA)
... (and other three disks)

However, booting a NetBSD 6.1.5 kernel, all drives are recognized and are 
usable with no problems at all. The only difference is that the "ignoring 
broken port multiplier support" message isn't reported by the 6.1.5 
kernel.

While trying to figure out what was wrong, I tried completely different 
drives, different SATA cables, a different power supply, et cetera, and 
nothing mattered except changing the kernel.

Does anyone have ideas about what may've broken this?

Thanks,
John