Linux uses PIO instead of DMA

[copy]

A problem in the IDE controller causes Linux (tested on a 2.4 and a 3.x kernel) to use PIO mode instead of DMA. This is the case both for ATAPI commands (send using ATA_CMD_PACKET) and the standard ATA commands.

DMA could improve disk transfer speed dramatically.

[MarcinListkowski]

The following repeats a few times during Linux boot from HDD:

[ 133.721880] ata1.01: status: { DRDY }
[ 135.768012] ata1: soft resetting link
[ 135.927023] ata1.00: configured for PIO2
[ 135.930023] ata1.01: configured for PIO2
[ 135.931023] ata1.01: device reported invalid CHS sector 0
[ 135.932023] ata1: EH complete
[ 135.965025] udevd[146]: worker [153] terminated by signal 9 (Killed)
[ 135.971025] udevd[146]: worker [149] terminated by signal 9 (Killed)
[ 166.737961] ata1: drained 65536 bytes to clear DRQ
[ 166.739968] ata1.01: limiting speed to PIO1
[ 166.739968] ata1.01: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
[ 166.740969] ata1.01: failed command: READ SECTOR(S)
[ 166.740969] ata1.01: cmd 20/00:08:80:ce:99/00:00:00:00:00/f0 tag 0 pio 4096 in
res 40/00:01:00:34:00/00:00:00:00:00/00 Emask 0x4 (timeout)

[copy]

@MarcinListkowski I see these messages too, but they don't seem to cause any problems (Linux simply tries reading the sector again).