Re: [BUG/RFC] SDHCI_QUIRK_NO_MULTIBLOCK for i.MX35/25

[Steffen Trumtrar <s.trumtrar@pengutronix.de>]

Hi Dong,

On Tue, Dec 17, 2013 at 07:43:26PM +0800, Dong Aisheng wrote:
> Hi Steffen,
> 
> On Fri, Nov 15, 2013 at 5:15 PM, Steffen Trumtrar
> <s.trumtrar@pengutronix.de> wrote:
> > Hi!
> >
> >
> > 1 Actual Use-Case
> > =================
> >
> >   I have a SDIO card with a Marvell 8787, that works fine on an i.MX53
> >   with the drivers/net/wireless/mwifiex/sdio.c driver. On an i.MX35
> >   however the loading of the firmware errors out on the very first
> >   single-block transfer with 1024 bytes payload.
> >
> >
> > 2 Reason for failure
> > ====================
> >
> >   sdhci defines SDHCI_QUIRK_NO_MULTIBLOCK to completely disable
> >   multi-block transfers for a host. The max_blk_count is simply set to 1
> >   to achieve this. Currently only i.MX35 and i.MX25 seem to be the only
> >   users of that quirk.  The quirk is used to fix an errata on these
> >   SoCs, that says, that "CMD12 abort operation does not abort data
> >   transfer on AHB". (ENGcm07207)
> >
> >   So, this is a problem regarding only SD and not SDIO.  On this special
> >   SDIO card, it looks like multi-block transfer has to be used for
> >   anything >16 bytes. Removing the quirk fixes the firmware loading
> >   error. The device is detected successfully after loading and can
> >   connect to an AP.
> >
> >
> > 3 Question
> > ==========
> >
> >   And here comes the question: What would be the correct approach to fix
> >   that and differentiate those two cases, so that we can use multi-block
> >   transfers with CMD53 but not with CMD25(?!) ?
> >
> >   1a. As I see no other users of that quirk, it might be okay to rename
> >       it, to better reflect the actual problem it fixes (broken CMD12 or
> >       something).
> >
> >   1b. When the host knows with what it deals with (SDIO or SD) set the
> >       max_blk_count according to the quirk. And only in the SD case, that is.
> >
> >   or
> >
> >   2. Introduce a max_blk_count_sd and max_blk_count_sdio and use them
> >      everywhere. Seems rather invasive and over the top.
> >
> >   or
> >
> >   3. something better.
> >
> 
> There's an .init_card callback which is called in mmc_sdio_init_card.
> That means we can know current card is SDIO, then you can try to
> update the max_blk_count there.
> 

>From what I can see, this seems to be the correct approach.
So, leave the quirk and in the sdio-case write a different max_blk_count ?!

Any objections to that ?

Steffen

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