MXC MMC driver and SDIO peripherals
dcbw at redhat.com
Mon Nov 2 15:00:32 EST 2009
On Thu, 2009-10-29 at 11:27 +0100, Daniel Mack wrote:
> On Wed, Oct 28, 2009 at 10:06:02AM -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, 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
> A number of bytes requested has bit 1 set indicates an error, according
> to the code if_sdio_prog_real(). Is there any more information in such
> cases? An error code that tells us about the real reason maybe?
Not that I know of; the helper is pretty simple. The v9 SD8686 vendor
driver assumes that any helper error is a CRC error, and retries that
block a few times before failing. But the helper asking for 17 bytes
seems a bit suspicious. Are you sure there aren't any TX/RX issues with
your SDHC and the connections to the card?
> > All the Marvell documentation (v5 at least) refers to 512-byte transfers
> > of the second-stage firmware in 32-byte blocks:
> > Section 22.214.171.124 of the v5 spec states:
> What documentation is that? Is it publically available?
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