Re: [PATCH] IDE 58

[Andre Hedrick]

Alan, we talked about this and the driver/hardware has a flaw.
If you count the total number of single IO operations to check
status/error et al., it is out right fugly.  Preprocessing will kill us
like today.

On Wed, 8 May 2002, Alan Cox wrote:

> > ata_channel (or ata_drive, but I doubt that would be really
> > necessary) a set of 4 access functions: taskfile_in/out for
> > access to taskfile registers (8 bits), and data_in/out for
> > steaming datas in/out of the data reg (16 bits).
> 
> Please push it higher level than that. Load the taskfile as a set in
> each method. Remember its 1 potentially paired instruction to do an MMIO
> write, its a whole mess of synchronziation and stalls to do a function 
> pointer.
> 
> > address at all (that is kill the array of port addresses) but
> > just pass the taskfile_in/out functions the register number
> > (cyl_hi, cyl_lo, select, ....) as a nice symbolic constant,
> > and let the channel specific implementation figure it out.
> 
> Pass  dev->taskfile_load() a struct at least for the common paths. Make the
> PIO block transfers also single callbacks for each block not word.
> 
> Alan
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Andre Hedrick
LAD Storage Consulting Group