1 files changed, 17 insertions, 7 deletions

diff --git a/drivers/mmc/host/davinci_mmc.c b/drivers/mmc/host/davinci_mmc.c
index 3bd0ba294e9d..547d29c31b40 100644
--- a/drivers/mmc/host/davinci_mmc.c
+++ b/drivers/mmc/host/davinci_mmc.c
@@ -137,15 +137,15 @@
 
 /*
  * One scatterlist dma "segment" is at most MAX_CCNT rw_threshold units,
- * and we handle up to NR_SG segments.  MMC_BLOCK_BOUNCE kicks in only
+ * and we handle up to MAX_NR_SG segments.  MMC_BLOCK_BOUNCE kicks in only
  * for drivers with max_hw_segs == 1, making the segments bigger (64KB)
- * than the page or two that's otherwise typical.  NR_SG == 16 gives at
- * least the same throughput boost, using EDMA transfer linkage instead
- * of spending CPU time copying pages.
+ * than the page or two that's otherwise typical. nr_sg (passed from
+ * platform data) == 16 gives at least the same throughput boost, using
+ * EDMA transfer linkage instead of spending CPU time copying pages.
  */
 #define MAX_CCNT        ((1 << 16) - 1)
 
-#define NR_SG           16
+#define MAX_NR_SG       16
 
 static unsigned rw_threshold = 32;
 module_param(rw_threshold, uint, S_IRUGO);
@@ -192,7 +192,7 @@ struct mmc_davinci_host {
         struct edmacc_param     tx_template;
         struct edmacc_param     rx_template;
         unsigned                n_link;
-        u32                     links[NR_SG - 1];
+        u32                     links[MAX_NR_SG - 1];
 
         /* For PIO we walk scatterlists one segment at a time. */
         unsigned int            sg_len;
@@ -202,6 +202,8 @@ struct mmc_davinci_host {
         u8 version;
         /* for ns in one cycle calculation */
         unsigned ns_in_one_cycle;
+        /* Number of sg segments */
+        u8 nr_sg;
 #ifdef CONFIG_CPU_FREQ
         struct notifier_block   freq_transition;
 #endif
@@ -568,6 +570,7 @@ davinci_release_dma_channels(struct mmc_davinci_host *host)
 
 static int __init davinci_acquire_dma_channels(struct mmc_davinci_host *host)
 {
+        u32 link_size;
         int r, i;
 
         /* Acquire master DMA write channel */
@@ -593,7 +596,8 @@ static int __init davinci_acquire_dma_channels(struct mmc_davinci_host *host)
         /* Allocate parameter RAM slots, which will later be bound to a
          * channel as needed to handle a scatterlist.
          */
-        for (i = 0; i < ARRAY_SIZE(host->links); i++) {
+        link_size = min_t(unsigned, host->nr_sg, ARRAY_SIZE(host->links));
+        for (i = 0; i < link_size; i++) {
                 r = edma_alloc_slot(EDMA_CTLR(host->txdma), EDMA_SLOT_ANY);
                 if (r < 0) {
                         dev_dbg(mmc_dev(host->mmc), "dma PaRAM alloc --> %d\n",
@@ -1202,6 +1206,12 @@ static int __init davinci_mmcsd_probe(struct platform_device *pdev)
 
         init_mmcsd_host(host);
 
+        if (pdata->nr_sg)
+                host->nr_sg = pdata->nr_sg - 1;
+
+        if (host->nr_sg > MAX_NR_SG || !host->nr_sg)
+                host->nr_sg = MAX_NR_SG;
+
         host->use_dma = use_dma;
         host->irq = irq;