ARM: MXC: mxcmmc: work around a bug in the SDHC busy line handling

MX3 SoCs have a silicon bug which corrupts CRC calculation of
multi-block transfers when connected SDIO peripheral doesn't drive the
BUSY line as required by the specs.

One way to prevent this is to only allow 1-bit transfers.

Another way is playing tricks with the DMA engine, but this isn't
mainline yet. So for now, we live with the performance drawback of 1-bit
transfers until a nicer solution is found.

This patch introduces a new host controller callback 'init_card' which
is for now only called from mmc_sdio_init_card().

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Volker Ernst <volker.ernst@txtr.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Michał Mirosław <mirqus@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 43eaf5ca5848..3196c84cc630 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -108,6 +108,9 @@ struct mmc_host_ops {
         int     (*get_cd)(struct mmc_host *host);
 
         void    (*enable_sdio_irq)(struct mmc_host *host, int enable);
+
+        /* optional callback for HC quirks */
+        void    (*init_card)(struct mmc_host *host, struct mmc_card *card);
 };
 
 struct mmc_card;