mtd: nand: omap2: Support parsing dma channel information from DT

Switch from dma_request_channel to allow passing dma channel
information from DT rather than hardcoding a value.

Also provide a handle to the GPMC's dev so it can be used to parse the DMA
channel information within the GPMC's DT node.

Performance Numbers via mtd_speedtest now that EDMA based prefetch works:

AM335x Performance numbers:
DMA
  CPULOAD Write: 54%  Read: 35%
  page write speed	-23% (vs non dma)
  page read speed	-35% (vs non dma)

NO DMA (prefetch-polled)
  CPULOAD Write: 98%  Read: 98%

AM437x Performance numbers:
DMA
  CPU LOAD Write: 56% Read: 36%
  page write speed	-16% (vs non dma)
  page read speed	-22% (vs non dma)

NO DMA (prefetch-polled)
  CPULOAD Write: 93%  Read: 93%

Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>

diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
index 08e1588..83b9091 100644 (file)
--- a/drivers/mtd/nand/omap2.c
+++ b/drivers/mtd/nand/omap2.c
@@ -118,8 +118,6 @@
 #define        PREFETCH_STATUS_FIFO_CNT(val)   ((val >> 24) & 0x7F)
 #define        STATUS_BUFF_EMPTY               0x00000001
 
-#define OMAP24XX_DMA_GPMC              4
-
 #define SECTOR_BYTES           512
 /* 4 bit padding to make byte aligned, 56 = 52 + 4 */
 #define BCH4_BIT_PAD           4
@@ -1808,7 +1806,6 @@ static int omap_nand_probe(struct platform_device *pdev)
        struct nand_chip                *nand_chip;
        int                             err;
        dma_cap_mask_t                  mask;
-       unsigned                        sig;
        struct resource                 *res;
        struct device                   *dev = &pdev->dev;
        int                             min_oobbytes = BADBLOCK_MARKER_LENGTH;
@@ -1921,8 +1918,8 @@ static int omap_nand_probe(struct platform_device *pdev)
        case NAND_OMAP_PREFETCH_DMA:
                dma_cap_zero(mask);
                dma_cap_set(DMA_SLAVE, mask);
-               sig = OMAP24XX_DMA_GPMC;
-               info->dma = dma_request_channel(mask, omap_dma_filter_fn, &sig);
+               info->dma = dma_request_chan(pdev->dev.parent, "rxtx");
+
                if (!info->dma) {
                        dev_err(&pdev->dev, "DMA engine request failed\n");
                        err = -ENXIO;