Comment 17 for bug 1810239

Created attachment 72217
Output of `dmesg' command

I have a MSI Z68A-GD80 B3 motherboard and when I try to enable Intel's IOMMU (kernel booted with intel_iommu=on), integrated Marvell 88SE9128 SATA controller doesn't work.

To reproduce:
1. Compile and prepare kernel with Intel IOMMU support enabled (CONFIG_INTEL_IOMMU=y).
2. Reboot the computer.
3. Enter BIOS and enable VT-d.
4. Boot the kernel with intel_iommu=on parameter.

Right after boot, kernel reports the following errors (SATA controller is at 0b:00.0):

[ 2.639774] DRHD: handling fault status reg 3
[ 2.639782] DMAR:[DMA Read] Request device [0b:00.1] fault addr fff00000
[ 2.639783] DMAR:[fault reason 02] Present bit in context entry is clear

After a while these entries appear:

[ 7.625837] ata14.00: qc timeout (cmd 0xa1)
[ 7.628341] ata14.00: failed to IDENTIFY (I/O error, err_mask=0x4)
[ 7.935483] ata14: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
[ 17.908407] ata14.00: qc timeout (cmd 0xa1)
[ 17.910935] ata14.00: failed to IDENTIFY (I/O error, err_mask=0x4)
[ 17.912276] ata14: limiting SATA link speed to 1.5 Gbps
[ 18.219077] ata14: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
[ 48.134607] ata14.00: qc timeout (cmd 0xa1)
[ 48.137508] ata14.00: failed to IDENTIFY (I/O error, err_mask=0x4)
[ 48.444646] ata14: SATA link up 1.5 Gbps (SStatus 113 SControl 310)

When there is a disk connected to the controller it does not work. When there are none, computer starts normally, apart from the huge lag caused by, presumably, probing the device.

Since this is the secondary controller on these motherboards, to eliminate those symptoms you can just plug disk in one of available ports of the built-in Intel SATA controller and disable Marvell's one using BIOS. The other work-around, if you need to use eSATA capabilities of the latter, is to disable VT-d techonology also using BIOS.