On Wed, 2009-10-28 at 17:47 +0100, Daniel Mack wrote: > On Wed, Oct 21, 2009 at 01:15:19PM -0700, Dan Williams wrote: > > On Wed, 2009-10-21 at 21:20 +0200, Daniel Mack wrote: > > > Hi, > > > > > > we're having trouble getting SDIO connected harware to fly on MX31 based > > > designs. In particular, a SD8686 chip supported by the libertas_sdio > > > driver will hang forever when built without CONFIG_MMC_DEBUG=y. With > > > that option selected, however, the behaviour is a little different, and > > > I can at least see the following messages on a recent 2.6.32-rc5 based > > > MX31 tree. > > > > > > Is there any common pitfall for such setups? I did more or less the same > > > thing on PXAs (same WLAN chip, same kind of interface, same firmware), > > > and haven't seen any such effects, so I suspect the MXC specific parts > > > to be the reason for that. Any ideas? > > > > Any idea what quirks your SDHC is using if any? Does it require PIO or > > can it do DMA? Does it have any transfer restrictions on block size or > > bit-width? What is the debug output of the MMC stack when loading the > > module for your SDHC? > > 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... Dan > Btw - there's a number of things missing for SDIO in the MXC MMC driver > which I implemented/fixed. I'll send patches as soon as I have more > confidence about the whole setup. > > > Thanks, > Daniel > > > [1] Errata IDs TLSbo91748 and TLSbo78667 from > http://www.freescale.com/files/32bit/doc/errata/MCIMX31CE.pdf?fpsp=1 > > > _______________________________________________ > libertas-dev mailing list > libertas-dev@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/libertas-dev -- 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
