mmc: sdhci: work around broken dma boundary behavior

Some SD host controllers (noticed on an integrated JMicron SD reader on an
HP Pavilion dv5-1250eo laptop) don't update the dma address register before
signaling a dma interrupt due to a dma boundary. Update the register
manually to the next boundary (by default 512KiB), at which the transfer
stopped.

As long as each transfer is at most 512KiB in size (guaranteed by a BUG_ON
in sdhci_prepare_data()) and the boundary is kept at the default value,
this fix is needed at most once per transfer. Smaller boundaries are taken
care of by counting the transferred bytes.

Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=28462

Signed-off-by: Mikko Vinni <mmvinni@yahoo.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 25e8bde600d1..85750a94c612 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -202,6 +202,12 @@
 #define SDHCI_MAX_DIV_SPEC_200  256
 #define SDHCI_MAX_DIV_SPEC_300  2046
 
+/*
+ * Host SDMA buffer boundary. Valid values from 4K to 512K in powers of 2.
+ */
+#define SDHCI_DEFAULT_BOUNDARY_SIZE  (512 * 1024)
+#define SDHCI_DEFAULT_BOUNDARY_ARG   (ilog2(SDHCI_DEFAULT_BOUNDARY_SIZE) - 12)
+
 struct sdhci_ops {
 #ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS
         u32             (*read_l)(struct sdhci_host *host, int reg);