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-rw-r--r--drivers/mmc/host/davinci_mmc.c24
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;