mtd: fsl-quadspi: improve read performance by increase AHB transfer size

Set AHB transfer size to 1K which improved the read performance.

Add ahb_buf_size field in fsl_qspi_devtype_data to denote the size for
different SoC.

Before:

root@imx6qdlsolo:~# dd if=/dev/mtd1 of=/dev/null bs=1M count=16
16+0 records in
16+0 records out
16777216 bytes (17 MB) copied, 0.472183 s, 25.1 MB/s

After:

root@imx6qdlsolo:~# dd if=/dev/mtd1 of=/dev/null bs=1M count=16
16+0 records in
16+0 records out
16777216 bytes (17 MB) copied, 0.369439 s, 29.5 MB/s

Signed-off-by: Allen Xu <b45815@freescale.com>
Signed-off-by: Huang Shijie <shijie8@gmail.com>
Signed-off-by: Frank Li <Frank.Li@freescale.com>
Acked-by: Huang Shijie <shijie.huang@intel.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

diff --git a/drivers/mtd/spi-nor/fsl-quadspi.c b/drivers/mtd/spi-nor/fsl-quadspi.c
index b1cc182..1c7308c 100644 (file)
--- a/drivers/mtd/spi-nor/fsl-quadspi.c
+++ b/drivers/mtd/spi-nor/fsl-quadspi.c
@@ -57,7 +57,9 @@
 
 #define QUADSPI_BUF3CR                 0x1c
 #define QUADSPI_BUF3CR_ALLMST_SHIFT    31
-#define QUADSPI_BUF3CR_ALLMST          (1 << QUADSPI_BUF3CR_ALLMST_SHIFT)
+#define QUADSPI_BUF3CR_ALLMST_MASK     (1 << QUADSPI_BUF3CR_ALLMST_SHIFT)
+#define QUADSPI_BUF3CR_ADATSZ_SHIFT            8
+#define QUADSPI_BUF3CR_ADATSZ_MASK     (0xFF << QUADSPI_BUF3CR_ADATSZ_SHIFT)
 
 #define QUADSPI_BFGENCR                        0x20
 #define QUADSPI_BFGENCR_PAR_EN_SHIFT   16
@@ -198,18 +200,21 @@ struct fsl_qspi_devtype_data {
        enum fsl_qspi_devtype devtype;
        int rxfifo;
        int txfifo;
+       int ahb_buf_size;
 };
 
 static struct fsl_qspi_devtype_data vybrid_data = {
        .devtype = FSL_QUADSPI_VYBRID,
        .rxfifo = 128,
-       .txfifo = 64
+       .txfifo = 64,
+       .ahb_buf_size = 1024
 };
 
 static struct fsl_qspi_devtype_data imx6sx_data = {
        .devtype = FSL_QUADSPI_IMX6SX,
        .rxfifo = 128,
-       .txfifo = 512
+       .txfifo = 512,
+       .ahb_buf_size = 1024
 };
 
 #define FSL_QSPI_MAX_CHIP      4
@@ -584,7 +589,12 @@ static void fsl_qspi_init_abh_read(struct fsl_qspi *q)
        writel(QUADSPI_BUFXCR_INVALID_MSTRID, base + QUADSPI_BUF0CR);
        writel(QUADSPI_BUFXCR_INVALID_MSTRID, base + QUADSPI_BUF1CR);
        writel(QUADSPI_BUFXCR_INVALID_MSTRID, base + QUADSPI_BUF2CR);
-       writel(QUADSPI_BUF3CR_ALLMST, base + QUADSPI_BUF3CR);
+       /*
+        * Set ADATSZ with the maximum AHB buffer size to improve the
+        * read performance.
+        */
+       writel(QUADSPI_BUF3CR_ALLMST_MASK | ((q->devtype_data->ahb_buf_size / 8)
+                       << QUADSPI_BUF3CR_ADATSZ_SHIFT), base + QUADSPI_BUF3CR);
 
        /* We only use the buffer3 */
        writel(0, base + QUADSPI_BUF0IND);