Re: hda: irq timeout: status=0xd0 DMA question

[Mark Lord <lkml@rtr.ca>]

Nick Warne wrote:
..
> Feb 19 14:05:31 quake kernel: hda: irq timeout: status=0xd0 { Busy }
> Feb 19 14:05:31 quake kernel:
> Feb 19 14:05:31 quake smartd[405]: Device: /dev/hda, not capable of SMART 
> self-check
> Feb 19 14:05:31 quake smartd[405]: Sending warning via  mail to 
> root@localhost ...
> Feb 19 14:05:31 quake kernel: hda: status timeout: status=0xd0 { Busy }
> Feb 19 14:05:31 quake kernel:
> Feb 19 14:05:31 quake kernel: hda: DMA disabled
> Feb 19 14:05:31 quake kernel: hda: drive not ready for command
> Feb 19 14:05:33 quake kernel: ide0: reset: success
..
> I dunno what happened to the drive that time (this is the only logs of the 
> incident) and I turned DMA back on with hdparm - but my question is why is 
> DMA turned off and then left off after a reset?

When I wrote that code in the mid-1990s, the number one causes of drives
getting confused (and needing to be reset again), were improper DMA timings,
cablings, and buggy DMA firmware.

So at the time, since DMA was a newish feature for IDE, we figured that
turning it off after reset was a Good Thing(tm).

And it was.  A more modern implementation might try being more clever about
such stuff, and Tejun is working on something like that for libata.

In the meanwhile, you could have a shell script just loop in the background,
turning DMA back on periodically.  If you care.

Cheers