Re: [PATCH 1/3] libata: implement dev->acpi_init_gtm

[Tejun Heo <htejun@gmail.com>]

Tejun Heo wrote:
> Jeff Garzik wrote:
>> Tejun Heo wrote:
>>> Add dev->acpi_init_gtm and store initial GTM values on host
>>> initialization.  If the field is valid, ATA_PFLAG_INIT_GTM_VALID flag
>>> is set.  This is to remember BIOS/firmware programmed initial timing
>>> for later use before reset and mode configuration modify it.
>>>
>>> Signed-off-by: Tejun Heo <htejun@gmail.com>
>> It sounds like pata_via and pata_amd need a foo_save_initial_config()
>> much like AHCI, during which they would fill ppriv->init_gtm rather than
>> ap->init_gtm.  Thoughts?  Both drivers are calling ata_acpi_cbl()
>> themselves, permitting the possibility of ppriv->init_gtm.
>>
>> This avoids forcing everyone else to bear the memory cost in ata_port
>> for just these two drivers.
> 
> The memory overhead is pretty small and more importantly there isn't a
> good place to load initial GTM.  ACPI is associated with the host during
> host registration after all private host initialization is complete.
> When the EH gets invoked, the first thing which is done is forcing PIO0
> before initial reset.
> 
> Unless we add another hook, the only place to put this is in private
> ->error_handler().  A driver can check whether it's being called for the
> first time and record it in private structure, which isn't too pretty,
> so I thought doing it this way was fair tradeoff.

Jeff, do you agree or still think it's better done in LLDs?  I'm okay
either way.

Thanks.

-- 
tejun