Re: [PATCH 09/11] ahci: convert to new EH

[Tejun Heo <htejun@gmail.com>]

Jeff Garzik wrote:
> Tejun Heo wrote:
>> Convert AHCI to new EH.  Unfortunately, ICH7 AHCI reacts badly if IRQ
>> mask is diddled during operation.  So, freezing is implemented by
>> unconditionally clearing interrupt conditions while frozen.
> 
> For standard BMDMA hardware, you -absolutely must- stop DMA, before 
> doing -anything- else, including EH/recovery.
> 
> This sort of scenario will be quite common.  I would recommend doing so 
> on sata_sil, sata_promise, ...
>

AHCI problem seems to be my honest mistake.  I misinterpreted device 
failures as HBA failures.  For ahci and sata_sil24, making them forget 
about pending commands take time, so it's awkward to do while freezing. 
  And, as they are pretty modern controllers, I expect them to do the 
right thing when IRQ mask is diddled with.

For more traditional BMDMA controllers, I agree with you.  I'll turn off 
BMDMA in bmdma_freeze() before setting nIEN.  But, for sata_sil, I wanna 
  leave it as it is.  The code is tested on sil3112 and 3114 and both 
work fine.  It's not always possible but I wanna avoid adding code which 
isn't necessary to LLDDs.  After a while, nobody would remember why the 
code is there and people will assume sata_sil needs it, which isn't true.

-- 
tejun