Rockie's Android Porting Guide（4）——Add SD card to your system

Rockie's Android Porting Guide（4）——Add SD card to your system

Rockie Cheng

Andorid use vold to manage SD card and it is easy to use.
But I meet many troubles and finally find that the real problem is in the Linux Kernel.
Thanks to the Android Mail List.

Part I (kernel)

(1)make sure thus kernel configuration in MMC driver

CONFIG_MMC=y
# CONFIG_MMC_DEBUG is not set
CONFIG_MMC_UNSAFE_RESUME=y
# CONFIG_MMC_EMBEDDED_SDIO is not set
CONFIG_MMC_PARANOID_SD_INIT=y

#
# MMC/SD Card Drivers
#
CONFIG_MMC_BLOCK=y
CONFIG_MMC_BLOCK_BOUNCE=y
# CONFIG_MMC_BLOCK_PARANOID_RESUME is not set
# CONFIG_SDIO_UART is not set
# CONFIG_MMC_TEST is not set

#
# MMC/SD Host Controller Drivers
#
CONFIG_MMC_SDHCI=y

(2)Disable this option
General Setup -> Create deprecated sysfs layout for older userspace tools

Before I did this,vold showed a lot of trouble.
And ,my media_path is not right
media_path /devices/platform/s3c-sdhci.0/mmc_host:mmc0<--my path before turn off that option

media_path /devices/platform/s3c-sdhci.0/mmc_host/mmc0 <--this is the right one

Vold may be unhappy to accept my old path,and it didn't work.

D/vold    (   42): Accepted connection from framework
D/vold    (   42): dispatch_cmd(send_ums_status):
D/vold    (   42): dispatch_cmd(mount_volume:/sdcard):
E/vold    (   42): Cannot start volume '/sdcard' (volume is not bound)
D/MountListener(   59): handleEvent volume_nomedia:/sdcard
D/MountListener(   59): handleEvent ums_disabled
D/MountListener(   59): handleEvent ums_disconnected

(3) rebuild your linux kernel

PART II(android system)

(1) creat a vold.conf in build/target/board/idea6410

## vold configuration file for idea6410

volume_sdcard {
    ## This is the direct uevent device path to the SD slot on the device
media_path /devices/platform/s3c-sdhci.0/mmc_host/mmc0

    media_type     mmc
    mount_point    /sdcard
    ums_path       /devices/platform/usb_mass_storage/lun0
}

(2)add those below to AndroidBoard.mk

include $(CLEAR_VARS)
LOCAL_MODULE_CLASS := ETC
LOCAL_MODULE := vold.conf
LOCAL_SRC_FILES := $(LOCAL_MODULE)
include $(BUILD_PREBUILT)

(3)rebuild the system and check init.rc

service vold /system/bin/vold
    socket vold stream 0660 root mount

(4)enjoy

D/vold    (   42): Accepted connection from framework
D/vold    (   42): dispatch_cmd(send_ums_status):
D/vold    (   42): dispatch_cmd(mount_volume:/sdcard):
I/vold    (   42): Evaluating dev '/devices/platform/s3c-sdhci.0/mmc_host/mmc0/mmc0:e624/block/mmcblk0' for mountable filesystems for '/sdcard'
D/MountListener(   61): handleEvent volume_unmounted:/sdcard
D/MountListener(   61): handleEvent ums_disabled
D/MountListener(   61): handleEvent ums_disconnected
D/MountListener(   61): handleEvent volume_checking:/sdcard

 

Rockie Cheng

阿虚