Re: SII SATA request size limit

[CASINO_E <CASINO_E@teleline.es>]

Forgive me if I'm saying something stupid but, do you mean a special 
case for this controller in ide-dma.c:ide_build_dmatable()?

In this case, should not segment size and boundary be included in hwif 
so we can have a generic ide_build_dmatable() without dealing 
explicitly with special cases? We could initialize to the default for 
most controllers and set the values for the exceptions inside each 
particular driver.

----- Mensaje Original -----
De: Jens Axboe <axboe@suse.de>
Fecha: Lunes, Septiembre 15, 2003 10:47 am
Asunto: Re: SII SATA request size limit

> On Fri, Sep 12 2003, Eduardo Casino wrote:
> > Hi All,
> > 
> > I had a look at the NetBSD pciide.c driver and found this 
> interesting> bit of code:
> > 	
> > 	/*
> > 	 * Rev. <= 0x01 of the 3112 have a bug that can cause data
> > 	 * corruption if DMA transfers cross an 8K boundary.  This is
> > 	 * apparently hard to tickle, but we'll go ahead and play it
> > 	 * safe.
> > 	 */
> > 	if (PCI_REVISION(pa->pa_class) <= 0x01) {
> > 	        sc->sc_dma_maxsegsz = 8192;
> > 	        sc->sc_dma_boundary = 8192;
> > 	}
> > 
> > This is basically the same as setting hwif->rqsize to 15, but 
> the NetBSD
> 
> You can do much much better than that, it's pretty simply to just
> restrict the segment size and boundary if you have a controller with
> such a bug. And then you get the benefit of the larger requests too,
> it's basically not a performance hit at that point.
> 
> -- 
> Jens Axboe
> 
>