Re: [PATCH] pata_it8213: MWDMA0 is unsupported

[Sergei Shtylyov]

Bartlomiej Zolnierkiewicz wrote:

> > > > > MWDMA0 timings cannot be met with the PIIX based controller
> > > > > programming interface.
> > >
> > > > > This change should be safe as this is how we have been doing
> > > > > things in IDE it8213 host driver for years.
> > >
> > > > > Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx>
> > > > > ---
> > > > > Verified with the documentation (similar case as with pata_efar).

> > > > Uhhh, no...

> > > > Too many damn drivers.

> > > > Too much damn duplication.

> > > > Too much damn subtle differences here and there.

> > > > The hardware is probably fine for MWMDA0 when it comes to pata_{efar,it8213},
> > > > it just not documented properly in the data sheet.

> > >    How so with pata_efar? The active/recovery bitfields are still 2-bit 
> > > wide, no?

> > Yes but when TIMEx bit is disabled we are using XFER_PIO_SLOW timings.

   600 ns cycle vs spec'ed 480 ns? Is it really worth it?

> > All data sheets including original Intel ones are a complete crap when it
> > comes to explicitly documenting this behavior.

> OTOH all drivers set TIMEx for MWDMA0 currently.. ?

   ... which would give a grossly overclocked timing.

> --
> Bartlomiej Zolnierkiewicz

MBR, Sergei
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