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.
Regards,
Steffen
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