高通手机900E变砖救活方法及原理分析

救活神器——刷机工程线

使用普通数据线简单改造即可：

1. 将数据线外皮剥开

2. 将绿线（D+）和黑线（地线）的外皮剥开

3. 将剥开的绿线和地线短接即可。

用改造好的工程线连接手机和电脑，

然后长按开机键8秒以上，让手机重启。

手机在重启过程中运行SBL时会检测到D+和地线短接，

然后让手机进入EDL模式（强制下载模式、9008模式），

然后用正常的数据线连接手机和电脑，再用QFIL刷机即可。

代码支持：

1. BOOT.BF.3.3/boot_images/core/boot/secboot3/hw/msm8952/sbl1/sbl1_config.c

  boot_log_message(“USB D+ check, Start”);
  boot_log_start_timer();
  
  /* Check whether USB D+ line is grounded. If it is, then enter
     PBL Download mode */
  if(boot_usb_al_check_for_pbl_dload(0))
  {

    boot_dload_transition_pbl_forced_dload();
  }
  boot_log_stop_timer(“USB D+ check, Delta”);

2. 继续调用

BOOT.BF.3.3/boot_images/core/boot/secboot3/src/boot_extern_hsusb_interface.c

/*===========================================================================

**  Function :  boot_usb_al_check_for_pbl_dload

** ==========================================================================
*/
/*!
 * @brief   This function checks if the USB D+ line is grounded.
 * @param   core_id   –  [IN] USB core ID to initialize
 * @return  boolean – returns whether we should enter PBL EDL mode.
 */
boolean boot_usb_al_check_for_pbl_dload(uint32 core_id)
{

   return qhsusb_al_check_for_pbl_dload(core_id);
}

3. 继续调用

BOOT.BF.3.3/boot_images/core/wiredconnectivity/qhusb/src/al/qhsusb_al_bulk.c

boolean qhsusb_al_check_for_pbl_dload(uint32 core_id)
{

#ifdef FEATURE_RUMI_BOOT
   qhsusb_log_message(“usb:: not going for edl mode, pre-si mode”);
   return FALSE;
#else
   qhsusb_boot_log_message(“USB: qhsusb_al_check_for_pbl_dload”);
   if(qhsusb_dci_check_for_pbl_dload(core_id))
   {

    qhsusb_log_message(“usb:: going for EDL”);
    return TRUE;
   }
   return FALSE;
#endif

4. 最终调用

BOOT.BF.3.3/boot_images/core/wiredconnectivity/qhsusb/src/dci/qhsusb_dci_8976.c

//=============================================================================
/**
 * @function  qhsusb_dci_check_for_pbl_dload
 *
 * @brief Checks whether the device should be put into EDL mode or not
 *
 *
 * @param core_id
 *
 * @return boolean TRUE: if D+ is connected to GND
 *                 FALSE: if D+ is not connected to ground
 *                 FALSE: if VBus is absent 
 *                 FALSE: if charger type is other than SDP/CDP
 *
 * @ref ChipIdea spec “CI13612a HighSpeed USB OnTheGo Controller Core”:
 *      Chapter 3.6.16 PORTSCx , PHY type selection.
 *      Chapter 3.6.12 ULPI VIEWPORT , control the PHY from the USB Core.
 *
 */
//============================================================================
boolean qhsusb_dci_check_for_pbl_dload(uint32 core_id)

{

#ifdef FEATURE_FORCED_EDL_MODE_DISABLE
  //for Emulation and simulation this feature needs to be 
  //disabled
  qhsusb_log(QHSUSB_PBL_DLOAD_FEATURE_DISABLED_LOG, 0, 0);
  (void)dci_enable_external_vbus_config;
  (void)qhsusb_is_charger_type_sdp_or_cdp; 
  //Check whether USB cable is connected during boot up  
  return FALSE; 
#else

… …

}

关闭此功能的方法：

找个合适的地方定义FEATURE_FORCED_EDL_MODE_DISABLE即可。