From: Alan Cox There are three flags being set by default by the PIIX driver for speeds > PIO 1, and one not being cleared properly on fallback to PIO0. The most important one is the prefetch/post write control which only works for ATA and can do bad things with ATAPI. The patch does its best to set the flags correctly for drivers/ide. Its not 100% perfect but its closer than the original. 100% perfect requires proper IORDY handling but this isn't critical (and its not right in libata either .. yet) Signed-off-by: Alan Cox Cc: Sergei Shtylyov Cc: Bartlomiej Zolnierkiewicz Sergei Shtylyov said: > + { 0, 0 }, > + { 0, 0 }, > + { 1, 0 }, > + { 2, 1 }, > + { 2, 3 }, }; > > pio = ide_get_best_pio_mode(drive, pio, 5, NULL); BTW, there's quite obvious error here which leads to access outside of timings[] if somebody passes PIO mode 5 (or autotuning code finds out that drive supports PIO mode 5). Could have been fixed while at it... Those drives should be rare, though... > + } > master_data = master_data | (timings[pio][0] << 12) | (timings[pio][1] << 8); > } > pci_write_config_word(dev, master_port, master_data); Actually, there's one more serious issue with piix_tune_drive() -- it doesn't actually set the drive's own transfer mode. WBR, Sergei Signed-off-by: Andrew Morton --- drivers/ide/pci/piix.c | 31 ++++++++++++++++++++++--------- 1 file changed, 22 insertions(+), 9 deletions(-) diff -puN drivers/ide/pci/piix.c~ide-backport-piix-fixes-from-libata-into-the-legacy-driver drivers/ide/pci/piix.c --- a/drivers/ide/pci/piix.c~ide-backport-piix-fixes-from-libata-into-the-legacy-driver +++ a/drivers/ide/pci/piix.c @@ -223,13 +223,15 @@ static void piix_tune_drive (ide_drive_t u16 master_data; u8 slave_data; static DEFINE_SPINLOCK(tune_lock); + int control = 0; /* ISP RTC */ - u8 timings[][2] = { { 0, 0 }, - { 0, 0 }, - { 1, 0 }, - { 2, 1 }, - { 2, 3 }, }; + static const u8 timings[][2]= { + { 0, 0 }, + { 0, 0 }, + { 1, 0 }, + { 2, 1 }, + { 2, 3 }, }; pio = ide_get_best_pio_mode(drive, pio, 5, NULL); @@ -240,19 +242,30 @@ static void piix_tune_drive (ide_drive_t */ spin_lock_irqsave(&tune_lock, flags); pci_read_config_word(dev, master_port, &master_data); + + if (pio >= 2) + control |= 1; /* Programmable timing on */ + if (drive->media == ide_disk) + control |= 4; /* Prefetch, post write */ + if (pio >= 3) + control |= 2; /* IORDY */ if (is_slave) { master_data = master_data | 0x4000; - if (pio > 1) + if (pio > 1) { /* enable PPE, IE and TIME */ - master_data = master_data | 0x0070; + master_data = master_data | (control << 4); + } else { + master_data &= ~0x0070; + } pci_read_config_byte(dev, slave_port, &slave_data); slave_data = slave_data & (hwif->channel ? 0x0f : 0xf0); slave_data = slave_data | (((timings[pio][0] << 2) | timings[pio][1]) << (hwif->channel ? 4 : 0)); } else { master_data = master_data & 0xccf8; - if (pio > 1) + if (pio > 1) { /* enable PPE, IE and TIME */ - master_data = master_data | 0x0007; + master_data = master_data | control; + } master_data = master_data | (timings[pio][0] << 12) | (timings[pio][1] << 8); } pci_write_config_word(dev, master_port, master_data); _