Libertas driver performance on Samsung platform

Dan Williams dcbw at
Mon Nov 16 01:32:04 EST 2009

On Mon, 2009-11-16 at 09:43 +0800, Jacky Lam wrote:
> Dan Williams 提到:
> > On Fri, 2009-11-13 at 13:12 +0800, Jacky Lam wrote:
> >> Dear all,
> >>
> >> 	I have read the previous mail about the low performance of Samsung
> >> BSP's SDIO platform driver when working with Libertas. I want to know if
> >> anyone have tried the kernel mainstream's Samsung driver and have any
> >> improvement on that?
> >
> > Does the Samsung SDHC have quirks or limitations with respect to DMA,
> > block size, transfer width, etc?
> >
> > Dan
> >
> >
> >
> >
> Dear Dan,
> 	I look through the source code and can't find any "special" limitation
> for the DMA, block size, transfer width.....Maybe I am not familiar
> enough with Linux MMC stack. Could you tell me if there is any
> requirement for the MMC stack on the host's DMA, block size, transfer
> width..etc? So, I can pinpoint my investigation?

There's no requirement in the stack, but the libertas driver and
firmware expect multi-block transfer ability and interrupt support.  The
libertas firmware will fail to load if if the host controller doesn't
support multi-block, which we just found to be a limitation of one of
the i.MX platform for example.


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