ASUS M2A-VM (SB600): AHCI setting in BIOS; AHCI and UDMA and `softreset failed (device not ready)`

[Paul Menzel <paulepanter@users.sourceforge.net>]

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Dear Linux folks,


please keep my address in CC list since I am not subscribed.

I am sorry for asking again for clarification for messages from Linux in
`/var/log/kern.log`.

        Jan 13 02:13:15 joe kernel: [    1.477687] ahci 0000:00:12.0: version 3.0

Whose version is this indication? Looking at the Wikipedia article [1]
and the AHCI link therein [2], specification numbers seem to 1.x.

Additionally having a sentence there, like `chipset support AHCI version
3.0` would be “better” in my opinion. If you agree, I can send a patch.

        Jan 13 02:13:15 joe kernel: [    1.477718] ahci 0000:00:12.0: PCI INT A -> GSI 22 (level, low) -> IRQ 22
        Jan 13 02:13:15 joe kernel: [    1.477748] ahci 0000:00:12.0: ASUS M2A-VM: enabling 64bit DMA
        Jan 13 02:13:15 joe kernel: [    1.477981] ahci 0000:00:12.0: AHCI 0001.0100 32 slots 4 ports 3 Gbps 0xf impl SATA mode
        Jan 13 02:13:15 joe kernel: [    1.477986] ahci 0000:00:12.0: flags: 64bit ncq sntf ilck pm led clo pmp pio slum part ccc 
        Jan 13 02:13:15 joe kernel: [    1.479052] scsi2 : ahci
        Jan 13 02:13:15 joe kernel: [    1.479142] scsi3 : ahci
        Jan 13 02:13:15 joe kernel: [    1.479220] scsi4 : ahci
        Jan 13 02:13:15 joe kernel: [    1.479296] scsi5 : ahci
        Jan 13 02:13:15 joe kernel: [    1.479434] ata3: SATA max UDMA/133 abar m1024@0xfe02f000 port 0xfe02f100 irq 22
        Jan 13 02:13:15 joe kernel: [    1.479438] ata4: SATA max UDMA/133 abar m1024@0xfe02f000 port 0xfe02f180 irq 22
        Jan 13 02:13:15 joe kernel: [    1.479442] ata5: SATA max UDMA/133 abar m1024@0xfe02f000 port 0xfe02f200 irq 22
        Jan 13 02:13:15 joe kernel: [    1.479447] ata6: SATA max UDMA/133 abar m1024@0xfe02f000 port 0xfe02f280 irq 22

So, AHCI and UDMA are unrelated? (Just to be sure once and for all. ;-))

        Jan 13 02:13:15 joe kernel: [    1.640626] ata1.00: ATAPI: TOSHIBA DVD-ROM SD-M1712, 1004, max UDMA/33
        Jan 13 02:13:15 joe kernel: [    1.656502] ata1.00: configured for UDMA/33
        Jan 13 02:13:15 joe kernel: [    1.796038] ata6: SATA link down (SStatus 0 SControl 300)
        Jan 13 02:13:15 joe kernel: [    1.796076] ata5: SATA link down (SStatus 0 SControl 300)
        Jan 13 02:13:15 joe kernel: [    1.796132] ata4: SATA link down (SStatus 0 SControl 300)
        Jan 13 02:13:15 joe kernel: [    1.808018] usb 2-1: new low speed USB device number 2 using ohci_hcd
        Jan 13 02:13:15 joe kernel: [    1.968017] ata3: softreset failed (device not ready)
        Jan 13 02:13:15 joe kernel: [    1.968063] ata3: applying PMP SRST workaround and retrying

This seems to be related to a hardware bug in the SB600 chipset [3]. The
discussion [4] indicates that setting `CONFIG_SATA_PMP=n` fixes this
issue. Although reading the option description [5] I do not understand
what it does and if it is advisable to disable it.

        […]
        
        Jan 13 02:13:15 joe kernel: [    2.140032] ata3: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
        Jan 13 02:13:15 joe kernel: [    2.146085] ata3.00: ATA-8: WDC WD20EARS-60MVWB0, 51.0AB51, max UDMA/100
        Jan 13 02:13:15 joe kernel: [    2.146088] ata3.00: 3907029168 sectors, multi 1: LBA48 NCQ (depth 31/32), AA
        Jan 13 02:13:15 joe kernel: [    2.146094] ata3.00: SB600 AHCI: limiting to 255 sectors per cmd
        Jan 13 02:13:15 joe kernel: [    2.152134] ata3.00: SB600 AHCI: limiting to 255 sectors per cmd
        Jan 13 02:13:15 joe kernel: [    2.152138] ata3.00: configured for UDMA/100

This seems to be related to [6], although the chipset SB600 seems to
support 3.0 Gbps instead of only 1.5 Gbps with the VIA K8T890. The drive
only seems to propagate UDMA/100 which is fine.

My main question is, that in the BIOS »Onboard SATA Type« is set to »IDE
Controller« by default. Is that true? But looking at the output AHCI
seems to be used nevertheless so the BIOS setting seems to be ignored or
does not make any difference to setting it to »AHCI«. So would changing
the option to »AHCI« give any benefit? Would it get rid of the
`softreset failed (device not ready)` too?


Thanks,

Paul


[1] https://en.wikipedia.org/wiki/Advanced_Host_Controller_Interface
[2] http://www.intel.com/technology/serialata/ahci.htm
[3] https://bugzilla.redhat.com/show_bug.cgi?id=468800
[4] http://www.linuxquestions.org/questions/linux-kernel-70/ata4-softreset-failed-device-not-ready-865155/
[5] http://cateee.net/lkddb/web-lkddb/SATA_PMP.html
[6] http://www.spinics.net/lists/linux-ide/msg41224.html

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