Re: [RFC][PATCH] at91_ide driver

[Stanislaw Gruszka <stf_xl@wp.pl>]

Wednesday 14 January 2009 13:58:32 Haavard Skinnemoen napisał(a):
> Stanislaw Gruszka wrote:
> > Some issues with driver:
> > 
> > * Why not platform driver
> > Generic pata/ide_platform driver will not work with AT91 as we need to 
> > do special things before access Task File and Data Register (functions 
> > set_8bit_mode() and set_16bit_mode()). Also extra things needs to be
> > done when changing PIO mode.
> 
> Why not use libata? There's already a pata_at32 driver there which
> should be usable on at91 with perhaps a few minor changes.

I will submit at91_ide for the mainline and not touch pata_at32  for reason
listed below (some of them was already mentioned in this thread):

* there are difference in h/w attend 
  - AT91 and AT32 static memory controller h/w is the same, but linux software 
    interface to programing SMC is diffrent (in this driver we need to program SMC)
  - AT91 have to switch between 8/16 bit data bus width, AT32 not
  - AT32 not need to have GPIO IRQ quirk
* libata have more overhead due to SCSI emulation
* ide maintainer is likely to accept at91_ide
* my company want to use it in production with older kernel

Cheers
Stanislaw Gruszka