Re: 32-bit IO to-do item...

[Jeff Garzik <jeff@garzik.org>]

Alan Cox wrote:
> On Thu, 09 Apr 2009 01:25:40 -0400
> Jeff Garzik <jeff@garzik.org> wrote:
> 
>> Alan,
>>
>> I keep meaning to mention this (and get it into the mail archive)... 
>> The 32-bit IO patch was incomplete, because it rendered 
>> ATA_IOC_[GS]ET_IO32 handling in ata_sas_scsi_ioctl() -- our base ioctl 
>> handler -- incorrect.
>>
>> Previously, it simply ensured the ioctls reflected hardcoded 16-bit I/O. 
>>   Now, behavior no longer matches what the ioctls report.
>>
>> At a minimum, drivers probably need to set an "I'm using 32bit I/O" 
>> flag, that the ioctl then reads, replacing ata_sas_scsi_ioctl()'s 
>> assumption that val==0.
> 
> Put onto my TODO list. I missed the fact you were even faking that
> rather bogus ioctl (what for example does a PIO over DMA device claim ??)

Probably as a result of a questionable choice to create new named 
constants ATA_IOC_* as a replacement for existing constants HDIO_*  I 
did that to avoid including linux/hdreg.h -- something we quickly wound 
up doing anyway.

I'd say pio-over-dma returns '1', so as to imply '0' meaning boring, 
slow, legacy compatible 16-bit I/O.  But it's a good question....

	Jeff