Re: irq-pio branch updated with Tejun's patches

[Albert Lee <albertcc@tw.ibm.com>]

Hi Tejun,

> 
> 
> This is sort of OT, but would it be possible to separate PIO
> issuing/interrupt handling from ata_qc_issue_prot and ata_host_intr?
> 

Isn't overriding the ->qc_issue() and ->irq_handle() in LLDD good enough?

> As PIO implementation currently stands, a lldd must use those standard
> methods to use PIO, but some controllers need PIO handling but the stock
> issue and interrupt routines don't really fit. e.g. not-yet-working
> sata_inic162x.  Something like ata_qc_issue_pio and ata_qc_pio_intr maybe?
> 

How about refactoring the PCI-IDE specific logic from libata-core to a 
seperate source file, say, ata_pciide.c?

Currently we have many PCI-IDE specific driving logic in libata-core.c.
Maybe we can seperate the different driving logic required by different
hardware interface into different source files?
This could make libata-core.c to be more abstract and generic from the underlying
hardware: libata-core only knows about the ata_port_operations interface.
(ata_port_operations should be generic enough to cover all the hardware types.)
LLDDs can either select default implementation for its hardware interface type
(such as ata_bmdma_setup() from ata_pciide.c) or override harddware specfic functions.

Ex. hardware interface types:
  - PCI IDE (bmdma + PRD tables)
    (covers legacy taskfile registers interface) => ata_pciide.c
  - ADMA     => pdc_adma.c
  - AHCI     => ahci.c
  - Initio   => sata_initio.c (ata_qc_issue_pio and ata_qc_pio_intr implementation here)
  - SAS/SATA => sata_sas.c (ata_sas_port_start/stop implementation here)
  - etc.     


Albert