[PLUG] harddisk dma modes, information using hdparm command

Kapil Pendse kapil.pendse at gmail.com
Thu Aug 14 06:27:26 PDT 2008


Hello,

I have a 2.5" toshiba harddisk connected to an ARM board (Samsung S3C2440
processor). It's running Linux 2.6.12. I need to find out whether the
harddisk is operating in PIO mode or in DMA mode. Can I get this information
using the "hdparm" command? Here's what I've found so far, need somebody to
tell me whether I'm right or not:

Bootup messages:
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Uniform Multi-Platform E-IDE driver Revision: 7.00alpha2
ide: Assuming 50MHz system bus speed for PIO modes; override with idebus=xx
SET CF & IDE WAIT!now BWSCON=225ed510
now begin cf_ide_init_default_hwifs()
Probing IDE interface ide0...
ide0: Wait for ready failed before probe !
Probing IDE interface ide0...
hda: TOSHIBA MK4025GAS, ATA DISK drive
ide0 at 0xc49c0020-0xc49c0027,0xc49c001c on irq 17
~~~~~~~~~~~~~~~~~~~~~~~~~~~

This seems to indicate that the harddisk is configured in PIO mode by
default.

Then after bootup, "hdparm -I /dev/ide/host0/bus0/target0/lun0/part1" prints
this:
~~~~~~~~~~~~~~~~~~~~~~~~~~~
ATA device, with non-removable media
Model Number: TOSHIBA MK4025GAS
Serial Number: 264E1388S
Firmware Revision: KA101A
Standards:
Supported: 6 5 4 3
Likely used: 6

<snip>

Capabilities:
LBA, IORDY(can be disabled)
bytes avail on r/w long: 48 Queue depth: 1
Standby timer values: spec'd by Standard, no device specific minimum
R/W multiple sector transfer: Max = 16 Current = ?
AdvancedPM level: unknown setting (0x0080)
DMA: sdma0 sdma1 sdma2 mdma0 mdma1 *mdma2 udma0 udma1 udma2 udma3 udma4
udma5
Cycle time: min=120ns recommended=120ns
PIO: pio0 pio1 pio2 pio3 pio4
Cycle time: no flow control=120ns IORDY flow control=120ns
<snip>
~~~~~~~~~~~~~~~~~~~~~~~~~~~

The "*mdma2" seems to indicate that it's working in multiword DMA mode 2.

So which mode is it operating in: PIO or DMA?
If it is in PIO mode, how do I set it to DMA mode by default (on bootup)?
Any init command/script that needs to be modified?

Thanks and best regards,
Kapil Pendse


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