MMC on SPI (MPC8313) slow reading

[Jean-Michel Hautbois]

Hi list,

I am currently using a MPC8313 with an MMC slot on SPI bus.
My fsl is the following :
spi at 7000 {
                        #address-cells = <1>;
                        #size-cells = <0>;
                        cell-index = <0>;
                        compatible = "fsl,spi";
                        reg = <0x7000 0x1000>;
                        interrupts = <16 0x8>;
                        interrupt-parent = <&ipic>;
                        mode = "cpu";
                        /* Chip Selects */
                        gpios = <&gpio1 15 0>;
                        bus-num = "0";

                        mmc-slot at 0 {
                                compatible = "fsl,mpc8313-mmc-slot",
                                             "mmc-spi-slot";
                                reg = <0>;
                                /* Card-Detect GPIO */
                                gpios = <&epld_stat6 7 1>;

                                voltage-ranges = <3300 3300>;
                                spi-max-frequency = <41665000>;
                        };
};

When I read a file (some MBytes) from an SD card, I read at something
like 240kBytes/sec.
This is really slow, and I would like to be sure that I cannot have
better performances.
FYI the reading time on the same SD card on a laptop is about 20MBytes/sec.

Thanks in advance for your help !
Regards,
JM