PATCH: Config option to pad SDIO sizes

Dan Williams dcbw at
Fri Jun 27 11:41:36 EDT 2008

On Fri, 2008-06-27 at 11:37 -0400, Dan Williams wrote:
> On Fri, 2008-06-27 at 15:22 +0200, Johan Adolfsson wrote:
> > Hi,
> > Attached is a patch agains 2.6.25 that adds a CONFIG_LIBERTAS_SDIO_PAD_SIZE
> > option to control padding of sdio packet sizes to work around buggy SDIO 
> > controllers - they are known to exist.. and not always possible to fix in
> > the
> > SDIO driver it seems.
> > 
> > Perhaps the patch could be trimmed a little - any sane compiler would
> > make it a noop if the PAD_SIZE is 0.
> Pending a look from Pierre, but I think this would probably _also_ be
> better as a module parameter rather than a CONFIG option.  Since the
> addition is done anyway, there shouldn't be a real speed hit.  The
> problem is that in the general world, we have no idea what hardware
> you'll be running this on, and it's better to have one kernel that can
> run on lots of hardware rather than having to flip config options and
> recompile.  I don't think a module parameter would be an issue in
> embedded-land either, right?
> Pierre, is there a better way to fix the crappy SDIO host controller
> thing, or is padding in libertas_sdio what we're stuck with?

Bonus points if we could change the pad size at runtime by doing
something like:

echo 0x03 > /sys/module/libertas_sdio/parameters/lbs_sdio_padsize

since RO module parameters are almost as bad as config options.  Not
sure how that plays with locking internally though.


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