获取串口log过程
SecureCRT 配制
波特率：92160
RTS/CTS
串口线
1. 黑线：GND
2. 蓝线：RX (板子recive)
3. 白线：TX（板子send）
串口log信息
[1380] DISP/ DSI read long packet size: 3
lcm_compare_id,lk ST7701S id = 0x88,id1 = 0x 2
[ 1.534724]<3>.(2)[1:swapper/0][DDP/IRQ]register callback on 0
[ 1.535214]<3>.(2)[1:swapper/0][DEVINFO LCM]Num:[0] type:[LCM] module:[JD-45FS0005-V0] vendor:[JUNDA] ic:[ILI9806E] info:[480*854] used:[false]
[ 1.535231]<3>.(2)[1:swapper/0][DEVINFO LCM]Num:[1] type:[LCM] module:[TXDY450SFWPC-15] vendor:[TONGXINGDA] ic:[FL10802] info:[480*854] used:[false]
[ 1.535245]<3>.(2)[1:swapper/0][DEVINFO LCM]Num:[2] type:[LCM] module:[(null)] vendor:[(null)] ic:[(null)] info:[(null)] used:[true]
[ 1.535253]<3>.(2)[1:swapper/0][DISP]func|disp_lcm_probe
[ 1.535261]<3>.(2)[1:swapper/0][DISPCHECK]plcm_name=st7701_fwvga_dsi_vdo_gt
[ 1.535312]<3>.(2)[1:swapper/0][DISP][disp_lcm_probe #230]ERROR:FATAL ERROR: can't found lcm driver:st7701_fwvga_dsi_vdo_gt in linux kernel driver
[ 1.535326]<3>.(2)[1:swapper/0][DISPCHECK][LCM], name: st7701_fwvga_dsi_vdo_gt
[ 1.535334]<3>.(2)[1:swapper/0][DISPCHECK][LCM] resolution: 480 x 854
[ 1.535342]<3>.(2)[1:swapper/0][DISPCHECK][LCM] physical size: 0 x 0
[ 1.535350]<3>.(2)[1:swapper/0][DISPCHECK][LCM] physical size: 0 x 0
[ 1.904048]<2>.(0)[100:frame_update_wo][DEVINFO LCM]registe LCM device!num:<0> type:<LCM> module:<JD-45FS0005-V0> vendor<JUNDA> ic<ILI9806E> version<(null)> info<480*854> used<false>
[ 1.904057]<2>.(0)[100:frame_update_wo][DEVINFO] devinfo_check!
[ 1.904122]<2>.(0)[100:frame_update_wo][DEVINFO LCM]registe LCM device!num:<1> type:<LCM> module:<TXDY450SFWPC-15> vendor<TONGXINGDA> ic<FL10802> version<(null)> info<480*854> used<false>
[ 1.904129]<2>.(0)[100:frame_update_wo][DEVINFO] devinfo_check!
[ 1.904137]<2>-(0)[100:frame_update_wo][DEVINFO] dev type:LCM
[ 1.904143]<2>-(0)[100:frame_update_wo][DEVINFO] dev list type:LCM
[ 1.904157]<2>.(0)[100:frame_update_wo][DEVINFO LCM]registe LCM device!num:<2> type:<LCM> module:<(null)> vendor<(null)> ic<(null)> version<(null)> info<(null)> used<true>
[ 1.904163]<2>.(0)[100:frame_update_wo][DEVINFO] devinfo_check!
[ 1.904171]<2>-(0)[100:frame_update_wo][DEVINFO] dev type:LCM
[ 1.904177]<2>-(0)[100:frame_update_wo][DEVINFO] dev list type:LCM
[ 1.904192]<2>-(0)[100:frame_update_wo]Unable to handle kernel NULL pointer dereference at virtual address 00000000
[ 1.904199]<2>-(0)[100:frame_update_wo]pgd = c0004000
[ 1.904211]<2>-(0)[100:frame_update_wo][00000000] *pgd=00000000
[ 1.904223]<2>-(0)[100:frame_update_wo][KERN Warning] ERROR/WARN forces debug_lock off!
M]Num:[2] type:[LCM] module:[(null)] vendor:[(null)] ic:[(null)] info:[(null)] used:[true]
registe LCM device!num:<2> type:<LCM> module:<(null)> vendor<(null)> ic<(null)> version<(null)> info<(null)> used<true>
Unable to handle kernel NULL pointer dereference at virtual address 00000000
从log信息来看，是我们刚添加的lcm节点信息问题，lcm节点没有数据，导致空指针异常。
log来源函数
下面是lcm节点信息传入的函数，由于该函数没有检测空指针问题而导致异常。
kernel/drivers/dev_info/dev_info.c
/*********************************************************************************
* This functions is designed to check if declared already, and add new device if not yet;
* Input: devinfo_struct
* Output: 1 / 0
* Note: return 1 for there have a same device registed,0 for new device
* *******************************************************************************/
int devinfo_check_add_device(struct devinfo_struct *dev)
{
int result = 0;
unsigned long irqflags;
struct devinfo_struct *dev_all;
printk("[DEVINFO] devinfo_check!\n");
spin_lock_irqsave(&dev_lock, irqflags);
if(list_empty(&active_devinfo_list) != 1)
list_for_each_entry(dev_all, &active_devinfo_list, device_link) {
printk("[DEVINFO] dev type:%s\n",dev->device_type);
printk("[DEVINFO] dev list type:%s\n",dev_all->device_type);
if((strcmp(dev_all->device_type,dev->device_type)==0) && (strcmp(dev_all->device_module,dev->device_module)==0) &&
(strcmp(dev_all->device_vendor,dev->device_vendor)==0) && (strcmp(dev_all->device_ic,dev->device_ic)==0) &&
(strcmp(dev_all->device_version,dev->device_version)==0) &&(strcmp(dev_all->device_info,dev->device_info)==0))// && shaohui mods here
// It will be replaced if there is a used device found! Do not mention HOT plug device! 2013.01.31
// (strcmp(dev_all->device_used,dev->device_used)==0))
{
if(strcmp(dev_all->device_used,dev->device_used)==0)
{
printk("[DEVINFO] find the same device\n");
}else if(strcmp(dev_all->device_used,DEVINFO_UNUSED)==0)
{
//we belive that we find a existed device! del the unexisted one!
printk("[DEVINFO] find device,but unused state!\n");
list_del(&dev_all->device_link);
list_add_tail(&dev->device_link, &active_devinfo_list);
// list_replace(&dev_all->device_link, &active_devinfo_list);
spin_unlock_irqrestore(&dev_lock, irqflags);
return 0;
}else{
//If a for-existed device is found lost,Do nothing~
printk("[DEVINFO] find device,but used state!\n");
}
spin_unlock_irqrestore(&dev_lock, irqflags);
return 1;
}
}
list_add_tail(&dev->device_link, &active_devinfo_list);
spin_unlock_irqrestore(&dev_lock, irqflags);
return 0;
}
为*#87#工模添加lcm节点信息
下面添加相对应的节点信息，解决空指针异常。
参考TP fl10802添加lcm节点信息
static void lcm_get_params(LCM_PARAMS *params)
{ // Video mode setting
params->dsi.intermediat_buffer_num = 2;
#ifdef SLT_DEVINFO_LCM
params->module="TXDY450SFWPC-15";
params->vendor="TONGXINGDA";
params->ic="FL10802";
params->info="480*854";
#endif
params->dsi.PS=LCM_PACKED_PS_24BIT_RGB888;
添加st7701 lcm节点信息
#if defined(LCT_ADD_TP_VERSION)
static int gtp_info_read_proc(struct file *file, char *buffer, size_t count, loff_t *ppos)
{
#LCM himax_852xES
#ifdef SLT_DEVINFO_LCM
params->module="TXDY450SFWPC-15";
params->vendor="TONGXINGDA";
params->ic="FL10802";
params->info="480*854";
#endif
...Wu_Being博客声明：本人博客欢迎转载，请标明博客原文和原链接！谢谢！
《移植mtk平台的lcm过程要点》： http://blog.csdn.net/u014134180/article/details/78124180
如果你看完这篇博文，觉得对你有帮助，并且愿意付赞助费，那么我会更有动力写下去。
