2012 nexus 7 無法開機

後來依照這一篇： https://support.google.com/nexus/troubleshooter/3337561?hl=zh-Hant
現象是：

按 power 沒反應。
插入 usb 沒出現 白電池。
長按 power 也沒反應。

所以依照上面的影片：

1. 插上usb 充電 一小時 (我充 5min)
2. 拔掉usb 再馬上插上
3. 按 power button 15 sec

結果終於出現 白電池。


充電真的是 asus 的死穴啊，記得TF101 也是這樣，放電太多就沒辦法充。

usb . some codes, about force full speed connect

driver 的 data : struct ehci_hcd, 內嵌在 struct usb_hcd 裡。
usb_hcd 是在 init_host_mode( ) 時 create 出來的。

hcd = usb_create_hcd(...)

compion_ports 是一個 bit variable, 每一個 bit 代表一個 port.
這個變數代表哪一個 port 歸 companion controller 管。


SET_CMF(PORTC1, reg_val, PFSC, 0x01);
這個 function 定義是：

#define SET_CMF(r, rv, c, v) rv = ((rv & ~r##_##c##_MASK) | (v << r##_##c##_OFFSET)) 

所以上面就變成..
PORTC1_PFSC_MASK 和 PORTC1_PFSC_OFFSET 的操作。

---

ehci_hcd.c -- include 一堆。
其中有 :

module_init(ehci_hcd_init);

所以這個大概是 driver 的本體(?)

include

• ehci-hub.c
• sucksoc_usb_hcd.c

另一個 driver 本體應該就是 socksoc_usb_driver.c ..

其中的 control register table 初始話就 是在 driver probe:

 rsc = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 
 usbcd_db->vaddr = (u8 *)ioremap(rsc->start, (rsc->end - rsc->start + 1));

---

datasheet , Port Status Control Register 中，有一個 Port Force Full Speed Connect.
可以限制 在 full speed 工作。

理論上只要 set 這個 bit，並且 keep 住，就可以讓 usb controller 工作在 full-speed.

但是這個 bit 在 controller reset 後就會被 clear。
所以要注意，reset 前要 先 save bit, 完後 restore

這樣找完所有的 code, 修改掉後，就可以讓 usb controller 工作在 full speed 了。

usb has_tt

usb driver 裡有一個 flag : has_tt.
tt 是 Transation Translater.
Wifi 說這個東西是 hub 用的。

hub 接到 High Speed 的 device 時，直接接到 up.
hub 接到 full speed 的 device 時，先經過 TT，再到 up

這是為了比免低速的 packet 站住大部分 up 的頻寬。
TT 會先用低速 buffer 住 full speed 的packet，再用 High Speed 送到 UP

Usb thumb driver

pchome..699 跟 450

kernel message 是：

usb 3-1.3.4: new high speed USB device using ehci_hcd and address 5
usb 3-1.3.4: New USB device found, idVendor=8564, idProduct=1000
usb 3-1.3.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 3-1.3.4: Product: Mass Storage Device
usb 3-1.3.4: Manufacturer: JetFlash
usb 3-1.3.4: SerialNumber: 
usb 3-1.3.4: configuration #1 chosen from 1 choice
scsi7 : SCSI emulation for USB Mass Storage devices
usb-storage: device found at 5
usb-storage: waiting for device to settle before scanning
usb-storage: device scan complete
scsi 7:0:0:0: Direct-Access     JetFlash Transcend 32GB   1100 PQ: 0 ANSI: 6
sd 7:0:0:0: Attached scsi generic sg5 type 0
61702144 512-byte logical blocks: (31.5 GB/29.4 GiB)
Write Protect is off
Mode Sense: 43 00 00 00

speed:

charles-chang@squeeze:~$ sudo hdparm -tT /dev/sde

/dev/sde:
 Timing cached reads:   14904 MB in  2.00 seconds = 7457.59 MB/sec
 Timing buffered disk reads: 102 MB in  3.03 seconds =  33.69 MB/sec
charles-chang@squeeze:~$ sudo hdparm -tT /dev/sde

/dev/sde:
 Timing cached reads:   9202 MB in  2.00 seconds = 4603.31 MB/sec
 Timing buffered disk reads: 102 MB in  3.04 seconds =  33.53 MB/sec
charles-chang@squeeze:~$ sudo hdparm -tT /dev/sde

/dev/sde:
 Timing cached reads:   14386 MB in  2.00 seconds = 7198.39 MB/sec
 Timing buffered disk reads: 102 MB in  3.04 seconds =  33.54 MB/sec

write:

charles-chang@squeeze:~/sd$ sudo dd if=/dev/zero of=tempfile bs=1M count=1024 conv=fdatasync,notrunc
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 65.8158 s, 16.3 MB/s

第2 支

kernel msg:

usb 3-1.3.4: USB disconnect, address 5
usb 3-1.3.4: new high speed USB device using ehci_hcd and address 6
usb 3-1.3.4: New USB device found, idVendor=125f, idProduct=312b
usb 3-1.3.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 3-1.3.4: Product: ADATA USB Flash Drive
usb 3-1.3.4: Manufacturer: ADATA
usb 3-1.3.4: SerialNumber: 000000000000
usb 3-1.3.4: configuration #1 chosen from 1 choice
scsi8 : SCSI emulation for USB Mass Storage devices
usb-storage: device found at 6
usb-storage: waiting for device to settle before scanning
usb-storage: device scan complete
scsi 8:0:0:0: Direct-Access     ADATA    USB Flash Drive  1.00 PQ: 0 ANSI: 6
sd 8:0:0:0: Attached scsi generic sg5 type 0
61739008 512-byte logical blocks: (31.6 GB/29.4 GiB)
Write Protect is off
Mode Sense: 23 00 00 00

speed:

charles-chang@squeeze:~$ sudo hdparm -tT /dev/sde

/dev/sde:
 Timing cached reads:   9560 MB in  2.00 seconds = 4782.52 MB/sec
 Timing buffered disk reads: 104 MB in  3.02 seconds =  34.49 MB/sec

write:

usb

原來 wusb 是 wireless usb 的意思。
-- 看來應該是掛了。

CFUN=0 trace:

static void requestRadioPower(void *data, size_t datalen, RIL_Token t) 

static void processRequest (int request, void *data, size_t datalen, RIL_Token t)
{
   ...
       case RIL_REQUEST_RADIO_POWER:
            requestRadioPower(data, datalen, t);
            break;

RIL_REQUEST_RADIO_POWER : ril_commands.h

    {RIL_REQUEST_RADIO_POWER, dispatchInts, responseVoid},

ril_commands.h : requestdatahandler.c

typedef struct CommandInfo {
    int requestId;
    void *(*dispatchFunction) (void *data, size_t datalen);
    void (*responseFunction) (void);
} CommandInfo;

/* RILD made me do it! */
static CommandInfo s_commandInfo[] = {
#include "ril_commands.h"
};

先查一下這些 ril 的 constant 定義在...

hardware/ril/include/telephony/ril.h

framework, java 的部份，是在:

framework/base/telephony/java/com/android/internal/telephony/RILConstants.java

為了怕兩邊定義不一致，這邊有 comment:

/*
cat include/telephony/ril.h | \
   egrep '^#define' | \
   sed -re 's/^#define +([^ ]+)* +([^ ]+)/    int \1 = \2;/' \
   >>java/android/com.android.internal.telephony/gsm/RILConstants.java
*/

回到 framework.. reference REQUEST_RADIO_POWER 的..

opt/telephony/src/java/com/android/internal/telephony/RIL.java

  setRadioPower(boolean on, Message result) {
 

3Gdongle 工作狀態 AT+CFUN

AT+CFUN AT command  sets the level of functionality in the MT. Level 
"full functionality" is where the highest level of power is drawn. 
"Minimum functionality" is where minimum power is drawn.

Possible values are,

0 - minimum functionality
1 - full functionality
2 - disable phone transmit RF circuits only
3 - disable phone receive RF circuits only
4 - disable phone both transmit and receive RF circuits

所以 ATCommand 在..

AT+CFUN?
+CFUN: 1
OK

就代表可以開始撥號了。