http://blog.chinaunix.net/uid-22547469-id-4859753.html
简单归纳一下吧，其实很简单。
第一：默认的dts文件有问题，
该status为okay：
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- sdhci@10130000 {
- compatible = "ralink,mt7620-sdhci";
- reg = <0x10130000 4000>;
- interrupt-parent = <&intc>;
- interrupts = <14>;
- status = "okay";
- };
第二步，make kernel_menuconfig，增加
Device Drivers->MMC/SD/SDIO card support->
*** MMC/SD/SDIO Card Drivers *** │ │
│ │ <*> MMC block device driver │ │
│ │ (8) Number of minors per block device │ │
│ │ [*] Use bounce buffer for simple hosts │ │
│ │ < > SDIO UART/GPS class support │ │
│ │ < > MMC host test driver │ │
│ │ *** MMC/SD/SDIO Host Controller Drivers *** │ │
│ │ < > Secure Digital Host Controller Interface support │ │
│ │ < > TI Flash Media MMC/SD Interface support │ │
│ │ < > MMC/SD/SDIO over SPI │ │
│ │ < > ENE CB710 MMC/SD Interface support │ │
│ │ < > VIA SD/MMC Card Reader Driver │ │
│ │ < > Synopsys DesignWare Memory Card Interface │ │
│ │ < > Renesas USDHI6ROL0 SD/SDIO Host Controller support │ │
│ │ <*> MTK SD/MMC │ │
│ │ [ ] MTK AEE KDUMP │ │
│ │ [*] Card Detect with Polling │ │
│ └─────────────────────────────────────
第三步：增加sdhc kmod相关模块，如下：
kmod-mmc
kmod-sdhci
kmod-sdhci-mt7620
好了，编译完后，大功告成，
对了，默认的openwrt针对MT7628的配置，native language不全，最好选以下几项：
kmod-nls-cp437
kmod-nls-iso8859-1
kmod-nls-utf8
好了， 
mount 后，如下图：
