[PATCH 06/22] mmc: omap_hsmmc: limit scatterlist size for sDMA autoloading

[Adrian Hunter]

The sDMA descriptor autoloading feature uses a fixed size
buffer to store descriptors for scatterlist segments.
That limits the scatterlist size to the maximum number
of descriptors that fit in the buffer.  The driver must
set this limit for upper layers to obey.

Signed-off-by: Adrian Hunter <adrian.hunter at nokia.com>
---
 drivers/mmc/host/omap_hsmmc.c |   15 ++++++++++++---
 1 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
index 114cd68..bab25ff 100644
--- a/drivers/mmc/host/omap_hsmmc.c
+++ b/drivers/mmc/host/omap_hsmmc.c
@@ -2239,9 +2239,18 @@ static int __init omap_hsmmc_probe(struct platform_device *pdev)
 			host->dma_caps |= DMA_TYPE_SDMA_DLOAD;
 	}
 
-	/* Since we do only SG emulation, we can have as many segs
-	 * as we want. */
-	mmc->max_segs = 1024;
+	if (host->dma_caps & DMA_TYPE_SDMA_DLOAD) {
+		unsigned int max = DMA_CTRL_BUF_SIZE /
+				   sizeof(struct omap_dma_sglist_node);
+
+		mmc->max_segs = 1 << (fls(max) - 1);
+	} else {
+		/*
+		 * Since we do only SG emulation, we can have as many segs as we
+		 * want.
+		 */
+		mmc->max_segs = 1024;
+	}
 
 	mmc->max_blk_size = 512;       /* Block Length at max can be 1024 */
 	mmc->max_blk_count = 0xFFFF;    /* No. of Blocks is 16 bits */
-- 
1.7.0.4