Re: [RFC PATCH] libata-sff: Fix oops reported in kerneloops.org for pnp devices with no ctl

[Jeff Garzik <jeff@garzik.org>]

Alan Cox wrote:
>>> Want me to roll a patch in that style ?
>> Works for me...
> 
> Ok
> 
> - Make ata_sff_altstatus private so nobody uses it by mistake
> - Drop the 400nS delay from it
> 
> Add
> 
> ata_sff_irq_status	-	encapsulates the IRQ check logic
> 
> This function keeps the existing behaviour for altstatus using devices. I
> actually suspect the logic was wrong before the changes but -rc isn't the
> time to play with that
> 
> ata_sff_sync		-	ensure writes hit the device
> 
> Really we want an io* operation for 'is posted' eg ioisposted(ioaddr) so
> that we can fix the nasty delay this causes on most systems.
> 
> - ata_sff_pause		-	400nS delay
> 
> Ensure the command hit the device and delay 400nS
> 
> - ata_sff_dma_pause
> 
> Ensure the I/O hit the device and enforce an HDMA1:0 transition delay.
> Requires altstatus register exists, BUG if not so we don't risk
> corruption in MWDMA modes. (UDMA the checksum will save your backside in
> theory)
> 
> The only other complication then is devices with their own handlers.
> rb532 can use dma_pause but scc needs to access its own altstatus
> register for internal errata workarounds so directly call the drivers own
> altstatus function.
> 
> 
> Signed-off-by: Alan Cox <alan@redhat.com>
> 
>  drivers/ata/libata-sff.c    |  115 +++++++++++++++++++++++++++++++++++++------
>  drivers/ata/pata_icside.c   |    2 -
>  drivers/ata/pata_rb532_cf.c |    4 +
>  drivers/ata/pata_scc.c      |    5 +-
>  include/linux/libata.h      |   16 +-----

applied