Most recent kernel where this bug did not occur: 2.6.15.4
Distribution: debian etch (testing)

Hardware Environment:
A system with PDC20376 and PDC20575 controllers and 4 sata devices.
2 seagate 7200.9 drives are connected to the PDC20376 and 2 seagate 7200.8
drives are connected to the PDC20575.

lspci output:
0000:00:00.0 Host bridge: VIA Technologies, Inc. VT8377 [KT400/KT600 AGP] Host
Bridge
0000:00:01.0 PCI bridge: VIA Technologies, Inc. VT8235 PCI Bridge
0000:00:07.0 FireWire (IEEE 1394): VIA Technologies, Inc. IEEE 1394 Host
Controller (rev 80)
0000:00:08.0 RAID bus controller: Promise Technology, Inc. PDC20376 (FastTrak
376) (rev 02)
0000:00:09.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5702X
Gigabit Ethernet (rev 02)
0000:00:0c.0 Mass storage controller: Promise Technology, Inc. PDC20575
(SATAII150 TX2plus) (rev 02)
0000:00:0d.0 Multimedia audio controller: Aureal Semiconductor Vortex 2 (rev fa)
0000:00:0f.0 Ethernet controller: Realtek Semiconductor Co., Ltd.
RTL-8139/8139C/8139C+ (rev 10)
0000:00:10.0 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1
Controller (rev 80)
0000:00:10.1 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1
Controller (rev 80)
0000:00:10.2 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1
Controller (rev 80)
0000:00:10.3 USB Controller: VIA Technologies, Inc. USB 2.0 (rev 82)
0000:00:11.0 ISA bridge: VIA Technologies, Inc. VT8235 ISA Bridge
0000:00:11.1 IDE interface: VIA Technologies, Inc.
VT82C586A/B/VT82C686/A/B/VT823x/A/C PIPC Bus Master IDE (rev 06)
0000:00:11.5 Multimedia audio controller: VIA Technologies, Inc.
VT8233/A/8235/8237 AC97 Audio Controller (rev 50)
0000:01:00.0 VGA compatible controller: Matrox Graphics, Inc. G400/G450 (rev 04)

I've got the following output with 2.6.15.4:
$ cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
  Vendor: ATA      Model: ST3250824AS      Rev: 3.AA
  Type:   Direct-Access                    ANSI SCSI revision: 05
Host: scsi1 Channel: 00 Id: 00 Lun: 00
  Vendor: ATA      Model: ST3500641AS      Rev: 2.AA
  Type:   Direct-Access                    ANSI SCSI revision: 05
Host: scsi2 Channel: 00 Id: 00 Lun: 00
  Vendor: ATA      Model: ST3300831AS      Rev: 3.02
  Type:   Direct-Access                    ANSI SCSI revision: 05
Host: scsi3 Channel: 00 Id: 00 Lun: 00
  Vendor: ATA      Model: ST3300831AS      Rev: 3.03
  Type:   Direct-Access                    ANSI SCSI revision: 05

Software Environment: linux 2.6.16
Problem Description: one sata device is not seen by the kernel

The device ST3500641AS is not seen with the kernel 2.6.16, and I've got the
following messages in the dmesg:

sata_promise 0000:00:08.0: version 1.03
ACPI: PCI Interrupt 0000:00:08.0[A] -> GSI 17 (level, low) -> IRQ 16
ata1: SATA max UDMA/133 cmd 0xF081A200 ctl 0xF081A238 bmdma 0x0 irq 16
ata2: SATA max UDMA/133 cmd 0xF081A280 ctl 0xF081A2B8 bmdma 0x0 irq 16
ata1: SATA link up 1.5 Gbps (SStatus 113)
ata1: dev 0 cfg 49:2f00 82:346b 83:7d01 84:4023 85:3469 86:3c01 87:4023 88:207f
ata1: dev 0 ATA-7, max UDMA/133, 488397168 sectors: LBA48
ata1: dev 0 configured for UDMA/133
scsi0 : sata_promise
ata2: SATA link up 1.5 Gbps (SStatus 113)
ata2 is slow to respond, please be patient
ata2 failed to respond (30 secs)
scsi1 : sata_promise
  Vendor: ATA       Model: ST3250824AS       Rev: 3.AA
  Type:   Direct-Access                      ANSI SCSI revision: 05