Messages in this thread | | | From | Bartlomiej Zolnierkiewicz <> | Subject | Re: [PATCH] pata_it8213: MWDMA0 is unsupported | Date | Thu, 26 Nov 2009 19:27:00 +0100 |
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On Thursday 26 November 2009 07:12:59 pm Sergei Shtylyov wrote: > 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@gmail.com> > >>>>>--- > >>>>>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?
960 ns actually
> >>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.
Except ata_piix which blacklists MWDMA0 for _all_ PATA controllers.. :)
I'm leaving my patches as they were for now, unless somebody wants to untangle this mess this is a safest and quickest way forward..
-- Bartlomiej Zolnierkiewicz
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