On Wed, Oct 28, 2009 at 10:11:04AM -0700, Dan Williams wrote: > On Wed, 2009-10-28 at 17:47 +0100, Daniel Mack wrote: > > I did some more research on this and it turns out that the problem is > > related to multi block transfers. At least, this is when it first > > occurs. > > > > The libertas SDIO driver downloads two firmwares to the device, one > > 'helper' and one 'real' firmware The first one only uses chunks of 64 > > bytes each and that seems to work fine. The real firmware, however, > > loads in 512 bytes chunks which the SDIO core breaks up into 16 blocks > > of 32 bytes. And this is where the MXC host controller bails out with a > > CRC error. Unfortunately, it does not give any more detailed information > > about what exactly went wrong. > > > > The effect might be related to an errata entry[1], which is what I'm > > currently investigating. To do so, I would like to limit the the > > communication to singe-block transfers, just to exclude all other > > possible (electrical, clock speed, ...) issues. I did that by setting > > mmc->max_blk_count to 1 in the the host controller, but then again, > > the libertas driver and/or the firmware doesn't like that and dies in > > if_sdio_pro_real() with > > > > firmware wants 17 bytes > > firmware helper signalled error > > > > Any idea how to get that working with only single block small transfers? > > Just a note; single-block transfers will probably kill your wifi > performance, especially if the errata are true. When the libertas > driver sends network data packets it sends them with > > ret = sdio_writesb(card->func, card->ioport, > packet->buffer, packet->nb); > > so if your packet is normal ethernet 1500 bytes, breaking that up in to > 47 single block transfers of 32-bytes each is going to be slow... Yep, I know. Thats's a disaster, especially without DMA enabled (which is currently the case). But I'd like to see it working somehow first and then see whether that's really the issue :) Daniel -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
