sunxi: mmc: increase status register polling rate for data transfers

With a recent bunch of SD3.0 cards in our A20-based board we
experienced data transfer rates of about 250 KiB/s instead of 10 MiB/s
with previous cards from the same vendor (both 4 GB/class 10). By
increasing status register polling rate from 1 kHz to 1 MHz we were
able to reach the original transfer rates again. With the old cards
we now even reach about 16 MiB/s.

Signed-off-by: Tobias Doerffel <tobias.doerffel@ed-chemnitz.de>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

diff --git a/drivers/mmc/sunxi_mmc.c b/drivers/mmc/sunxi_mmc.c
index ce2dc4ae41c363c6d2c597e54d66227dde2b9a04..3be9a90a6be4bb1121c6073add4ddb881516251e 100644 (file)
--- a/drivers/mmc/sunxi_mmc.c
+++ b/drivers/mmc/sunxi_mmc.c
@@ -269,18 +269,18 @@ static int mmc_trans_data_by_cpu(struct mmc *mmc, struct mmc_data *data)
        unsigned i;
        unsigned *buff = (unsigned int *)(reading ? data->dest : data->src);
        unsigned byte_cnt = data->blocksize * data->blocks;
-       unsigned timeout_msecs = byte_cnt >> 8;
-       if (timeout_msecs < 2000)
-               timeout_msecs = 2000;
+       unsigned timeout_usecs = (byte_cnt >> 8) * 1000;
+       if (timeout_usecs < 2000000)
+               timeout_usecs = 2000000;
 
        /* Always read / write data through the CPU */
        setbits_le32(&mmchost->reg->gctrl, SUNXI_MMC_GCTRL_ACCESS_BY_AHB);
 
        for (i = 0; i < (byte_cnt >> 2); i++) {
                while (readl(&mmchost->reg->status) & status_bit) {
-                       if (!timeout_msecs--)
+                       if (!timeout_usecs--)
                                return -1;
-                       udelay(1000);
+                       udelay(1);
                }
 
                if (reading)