SATA150TX4 atat1:command timeout

[Francois Payette <francoisp@netmosphere.net>]

Hi,

We have reported earlier a strange bug at bugzilla.kernel.org (#4106 
<http://bugzilla.kernel.org/show_bug.cgi?id=4106>): in our setup of a 
20318 (the SATA150 TX4, not the fastrack one) we are systematically 
getting ata1: command timeout after copying between 200 and 600GB of 
data through the controller. Our setup is with 4 maxtor 6Y200M0, 2 of 
them in raid 0, and the other 2 in a LV group over a raid 0 md array. 
When copying from one array to the other one repeatedly,  the machines 
freezes once out out of every 2 copy. We changed the drive order, but we 
still got the msg ata1 command timeout. We swapped the order of the 
cables, and still got ata1 command timeout. We got a few kernel panics 
with spin locks, but since finding this forum we added the line

writel(mask, mmio_base + PDC_INT_SEQMASK);

to pdc_interrupt, and that one was gone.

We have kernel 2.6.10-753 (fc3) with all relevant patches to the sata 
stuff, the last of which is the one Bartlomiej Zolnierkiewicz posted on 
06/02/2005. 
http://marc.theaimsgroup.com/?l=linux-ide&m=110769875419863&w=2 
<http://marc.theaimsgroup.com/?l=linux-ide&m=110769875419863&w=2>

After commenting out the line
    /* reduce TBG clock to 133 Mhz. */
    /*tmp = readl(mmio + PDC_TBG_MODE); */
    tmp &= ~0x30000; /* clear bit 17, 16*/
    tmp |= 0x10000;  /* set bit 17:16 = 0:1 */
    /*writel(tmp, mmio + PDC_TBG_MODE); */

in pdc_host_init (total shot in the dark) the setup seems more stable, 
we have now gone through 3 cycles of stress test (600GB of copying) and 
have not seen the crash.

Earlier we tried the same stress test with ATA_DEBUG and 
ATA_VERBOSE_DEBUG defined, the error did not occur  maybe because of it 
was slowed down with all the output)?

Later we tried  commenting out the line that sets bmr burst 
(PDC_FLASH_CTL) and slew rate (PDC_SLEW_CTL) in pdc_host_init, and that 
slowed the setup to half it's orignal speed, but in that case the 
problem did not show up.

We outputted the command timeout and it's  0x35 (ATA_CMD_WRITE_EXT) 
protocol is 4 (ATA_PROT_DMA).

Any ideas?
TIA,
Francois Payette