Re: libata PATA support - work items?

[Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>]

On Thu, 06 Jan 2005 21:29:42 +0000, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> On Iau, 2005-01-06 at 08:51, Albert Lee wrote:
> > For the 1st item,
> > - add PATA device errata/blacklist info
> > Is there any detail or draft design idea available?
> 
> There is a fair bit of code in drivers/ide. Most of it is handling drive
> problems that occurred with early DMA drives and it uses the
> model/firmware info in the ident string to match drives that claim to do
> DMA but do not and drives that claim not to but can.
> 
> The logic is fairly simple and the database is easily transported or
> shared. It is fairly important because some of these old drives
> corrupted data if used DMA. (see drivers/ide/ide-dma.c)
> 
> For PIO problem drives where there is a need to keep PIO modes chosen
> carefully then ide-lib has a list (ide_pio_blacklist) and the ide-io
> code knows about pio modes and older style EIDE cycle timing reports
> (ide_get_best_pio_mode)

There was some rumor (?) that this blacklist was created on CMD640
controller programmed with wrong timings...

BTW ide_get_best_pio_mode(), it is really misleading
(i.e. recent PIO tuning bug in it821x.c).

> IDE CD has some DMA blacklists for ATAPI but they should be viewed with
> caution as many entries were due to a bug in our atapi implementation
> that was fixed long ago.

There is only a common DMA blacklist in ide-dma.c.