SDIO performance

[Simon Twogood]

Hi Tim,

Using an Atmel AT91SAM9263 system-on-a-chip and Linux 2.6.27 I have be  
able to get speeds of roughly 0.8 MB/s. As a comparison, I was able to  
get 3.6 MB/s using the wired ethernet adapter on the same board.

My tests were far from perfect though, as I was just trying to get a  
rough idea of what kind of speeds I could get.

Simon


On 8-Jan-09, at 6:09 PM, Tim Harvey wrote:

> Greetings,
>
> Back in May of last year I was doing some evaluation of a couple of
> Marvell Libertas 88w8686 modules on an i.MX31 host running 2.6.22  
> using
> the libertas driver from compat-wireless.  I found at the time that  
> the
> max throughput I could achieve was about 1.1mbps at 11M and it was
> suggested that the fact that the i.MX31's SDIO host controller driver
> did not support MMC_CAP_SDIO_IRQ and could only support 1bit  
> transfers.
> Recently I've taken another look at the same sdio modules but this  
> time
> running on an OMAP3 beagleboard host running 2.6.27 using the libertas
> driver from mainline.  This time I find that I can only achieve about
> 0.8mbps at 11M.
>
> I've verified that the OMAP3's MMC/SDIO host controller driver  
> supports
> 4-bit mode yet it does not support MMC_CAP_SDIO_IRQ.  Its been  
> suggested
> to me on #libertas that the linux core sdio driver is not very  
> efficient
> and that also the libertas if_sdio.c support steps down to 1-bit mode
> for most transfers.  Even still 1bit SDIO has a data transfer rate of
> 10MB/sec so I'm still surprised at this <1mbps performance.
>
> Can anyone else using libertas-sdio tell me what hardware they are  
> using
> (host and module) and what software they are using (kernel version +  
> any
> relevant patches and libertas firmware) and what throughputs they can
> achieve?
>
> I'm going to be digging into the if_sdio.c component and try to
> understand the linux core sdio subsystem to see if I can find any hope
> of speeding things up
> - any pointers would be greatly appreciated.
>
> I've seen the recent patches to support GSPI devices and I wonder what
> kind of throughput has been acheived on those?
>
> Also, as about 8mo's have passed since I looked for hardware supported
> by the libertas driver, are there any recent USB dongle devices
> supported out there?  The information on
> http://linuxwireless.org/en/users/Drivers/libertas hasn't changed in
> quite some time and I'm not sure if its up-to-date.
>
> Thanks,
>
> Tim
>
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