[Galaxy Tab 7.7 General] cmmc:
Hi,

Let me start by saying that I just spend the last 7 hours searching everywhere on XDA and the net for this solution (!), but I really cannot find it. I've been a longtime reader of XDA and thought it was about time I posted something ;)

I am looking to modify one single file (!) to get the USB charging to work whilst my Tab 7.7 (6800 3G) is on. Apparently this fix works (have seen youtube proof on Tab 10.1), but I don't have a clue how to get around the permissions! I want to connect to a USB power source whilst out and about.

This is the solution I've found (quoted verbatim from galaxytabhacks.com):

Now, I have a rooted device and everything seems to work for me apart from actually editing/saving/creating a file in /sys/class/power_supply/battery. The file system is rewritable (rw) but whatever I do I can't edit the above file or create a new one in this folder. Installed busybox, installed all sorts of rw mount and root tools. Nothing works. Drives me nuts because I'm convinced that once I can do this trick it'll work! :confused:

$ export PATH=/data/local/bin:$PATH
$ su
# cd /sys/class/power_supply
# ls -l
lrwxrwxrwx root root 2012-05-13 15:37 ac -> ../../devices/platform/sec-battery/power_supply/ac
lrwxrwxrwx root root 2012-05-13 15:35 battery -> ../../devices/platform/sec-battery/power_supply/battery
lrwxrwxrwx root root 2012-05-13 15:37 max8997-charger -> ../../devices/platform/s3c2440-i2c.5/i2c-5/5-0066/max8997-charger/power_supply/max8997-charger
lrwxrwxrwx root root 2012-05-13 15:35 usb -> ../../devices/platform/sec-battery/power_supply/usb
# cd battery
# ls -l
-rw-rw-r-- root root 4096 2012-05-13 15:37 batt_current_now
-rw-rw-r-- root root 4096 2012-05-13 15:37 batt_full_check
-rw-rw-r-- root root 4096 2012-05-13 15:37 batt_lp_charging
-rw-rw-r-- root root 4096 2012-05-13 15:35 batt_temp
-rw-rw-r-- root root 4096 2012-05-13 15:37 batt_temp_check
-rw-rw-r-- root root 4096 2012-05-13 15:37 batt_type
-rw-rw-r-- root root 4096 2012-05-13 15:37 batt_vol
-r--r--r-- root root 4096 2012-05-13 15:35 capacity
-rw-rw-rw- root root 4096 2012-05-13 13:35 charging_source
lrwxrwxrwx root root 2012-05-13 15:37 device -> ../../../sec-battery
-rw-rw-r-- root root 4096 2012-05-13 15:37 fg_reg
-rw-rw-r-- root root 4096 2012-05-13 15:37 fg_soc
-r--r--r-- root root 4096 2012-05-13 15:35 health
-rw-rw-r-- root root 4096 2012-05-13 15:37 jig_on
drwxr-xr-x root root 2012-05-13 12:38 power
-r--r--r-- root root 4096 2012-05-13 15:35 present
-rw-rw-r-- root root 4096 2012-05-13 15:37 reset_cap
-rw-rw-r-- radio system 4096 2012-05-13 12:37 reset_soc
-rw-rw-r-- radio system 4096 2012-05-13 12:37 siop_activated
-r--r--r-- root root 4096 2012-05-13 15:35 status
lrwxrwxrwx root root 2012-05-13 15:37 subsystem -> ../../../../../class/power_supply
-r--r--r-- root root 4096 2012-05-13 15:37 technology
-r--r--r-- root root 4096 2012-05-13 15:37 type
-rw-r--r-- root root 4096 2012-05-13 15:37 uevent
-rw-rw-r-- root root 4096 2012-05-13 15:35 voltage_now
# echo 1 > charging_source
# cat charging_source
0
# echo 1 > force_usb_charging
cannot create force_usb_charging: directory nonexistent
# id
uid=0(root) gid=0(root)
# pd
pd: not found
# pwd
/sys/devices/platform/sec-battery/power_supply/battery
# mount
rootfs / rootfs rw,relatime 0 0
tmpfs /dev tmpfs rw,nosuid,relatime,mode=755 0 0
devpts /dev/pts devpts rw,relatime,mode=600 0 0
proc /proc proc rw,relatime 0 0
sysfs /sys sysfs rw,relatime 0 0
none /acct cgroup rw,relatime,cpuacct 0 0
tmpfs /mnt/asec tmpfs rw,relatime,mode=755,gid=1000 0 0
tmpfs /mnt/obb tmpfs rw,relatime,mode=755,gid=1000 0 0
none /dev/cpuctl cgroup rw,relatime,cpu 0 0
/dev/block/mmcblk0p9 /system ext4 rw,relatime,errors=panic,barrier=1,data=ordered 0 0
/dev/block/mmcblk0p10 /data ext4 rw,nosuid,nodev,noatime,barrier=1,data=ordered,noauto_da_alloc 0 0
/dev/block/mmcblk0p7 /cache ext4 rw,nosuid,nodev,noatime,barrier=1,data=ordered 0 0
/dev/block/mmcblk0p1 /efs ext4 rw,nosuid,nodev,noatime,barrier=1,data=ordered 0 0
/dev/block/mmcblk0p4 /mnt/.lfs j4fs rw,relatime 0 0
/sys/kernel/debug /sys/kernel/debug debugfs rw,relatime 0 0
/dev/fuse /mnt/sdcard fuse rw,nosuid,nodev,relatime,user_id=1023,group_id=1023,default_permissions,allow_other 0 0
tmpfs /mnt/sdcard/extStorages tmpfs ro,relatime,mode=755,gid=1000 0 0
/dev/block/vold/179:17 /mnt/sdcard/extStorages/SdCard vfat rw,dirsync,nosuid,nodev,noexec,relatime,uid=1000,gid=1023,fmask=0002,dmask=0002,allow_utime=0020,codepage=cp437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro 0 0
#

Model: GT-P6800

Android: 3.2

Baseband: DXLB1

Kernel: 2.6.36 stock (via ODIN), with root

Build: DXLB3

Any help would be most appreciated. If this works, I'm sure others will immediately benefit too! Thanks.

cmmc