Recommendation for PCMCIA (DMA capable) interface chipset
Steven John Newbury
steve at snewbury.org.uk
Fri Dec 21 18:49:56 EST 2007
On Fri, 2007-12-21 at 15:17 -0500, Iain Barker wrote:
> Russell King wrote:
> > No Linux kernels use DMA for PCMCIA/CF cards, no matter what
> > architecture or platform or chipset.
> > The only time you get DMA on such an interface is with Cardbus
> > cards which effectively extend the PCI programming interface
> > direct to the card.
> Thanks Russell. I'm looking into Cardbus adapters and also USB2 to PCMCIA as alternatives.
> Do you know if there are any chipsets which Linux supports at the higher PIO rates?
> libata appears to lock PCMCIA to PIO 0, whereas modern CF cards commonly report they support PIO 5 or 6 in their CIS data (the CFA extensions for 20 and 25MB/s).
Unfortunately the Linux ide-cs drivers only use the "standard" IO
timings rather than the timings as reported by the card CIS. This
severly limits the transfer rates possible with CF cards. I have
previously tried to get this working by using MMIO which supports
programmable access timings whereas the timings for the IO space are
fixed. The driver should then set the access speed according to the CIS
reported value. I couldn't get it delivering interrupts though for some
reason that I never figured out. Check back in the archives...
More information about the linux-pcmcia