Re: Kernel 2.6.37 erroneously limiting to UDMA/33

From: Robert Hancock
Date: Wed Jan 05 2011 - 18:50:21 EST

(CCing linux-ide)

On 01/05/2011 12:33 PM, Stephen Clark wrote:

Why is the kernel limiting me to udma/33 when the device says it can do
ata2.01: CFA: TRANSCEND, 20070831, max UDMA/66

There is no cable the compact flash is a socket on the motherboard!

The kernel has no way to know that, and presumably the board isn't connecting the signal for IDE pin 34 to ground in order to properly signal that an 80-wire cable (or equivalent) is connected so that speeds over UDMA33 can be used.

You should be able to use the libata.force=80c option on the kernel command line to override the cable detection.

Loading sd_mod.ko module
Loading libata.ko module
Loading ata_generic.ko module
Loading pata_acpi.ko module
pata_acpi 0000:00:0f.0: PCI INT B -> GSI 21 (level, low) -> IRQ 21
pata_acpi 0000:00:0f.0: PCI INT B disabled
Loading pata_via.ko module
scsi0 : pata_via
scsi1 : pata_via
ata1: PATA max UDMA/133 cmd 0x1f0 ctl 0x3f6 bmdma 0xfa00 irq 14
ata2: PATA max UDMA/133 cmd 0x170 ctl 0x376 bmdma 0xfa08 irq 15
ata2.01: CFA: TRANSCEND, 20070831, max UDMA/66
ata2.01: 7962192 sectors, multi 0: LBA
ata2.01: limited to UDMA/33 due to 40-wire cable
ata2.01: configured for UDMA/33
scsi 1:0:1:0: Direct-Access ATA TRANSCEND 2007 PQ: 0 ANSI: 5
sd 1:0:1:0: [sda] 7962192 512-byte logical blocks: (4.07 GB/3.79 GiB)
sd 1:0:1:0: [sda] Write Protect is off
sd 1:0:1:0: [sda] Write cache: disabled, read cache: enabled, doesn't
support DA
sda: sda1 sda2 sda3
sd 1:0:1:0: [sda] Attached SCSI disk
Loading ata_piix.ko module


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