[FAQ23368] 对最高频做降频-MT6853

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[DESCRIPTION]
有些客户需要降低最高频，那么修改gFreqTbl[].


[SOLUTION]
修改方法：

以6853平台为例，如果需要把最高频4266降低到3200.

1. /vendor/mediatek/proprietary/bootable/bootloader/preloader/platform/mt6853/src/drivers/dramc_pi_main.c
   
2.   DRAM_DFS_FREQUENCY_TABLE_T gFreqTbl[DRAM_DFS_SRAM_MAX] =
   
3. {
   
4.       {LP4_DDR3200 /*0*/, DIV8_MODE, SRAM_SHU1, DUTY_LAST_K,  VREF_CALI_OFF,  CLOSE_LOOP_MODE},  // highest freq of term group (3733) must k first.
   
5.       {LP4_DDR4266 /*1*/, DIV8_MODE, SRAM_SHU0, DUTY_NEED_K,  VREF_CALI_ON,   CLOSE_LOOP_MODE},  // highest freq of term group (3733) must k first.
   
6. ......
   
7. 
   
8. };

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需要修改最高频SRAM_SHU0对应的freq_sel, 默认SRAM_SHU0对应的freq_sel为LP4_DDR4266(4266Mhz)。
如果要把最高频4266降低到3200，需要把LP4_DDR4266改成LP4_DDR3200.

即：LP4_DDR4266 => LP4_3200

1. 
   
2. DRAM_DFS_FREQUENCY_TABLE_T gFreqTbl[DRAM_DFS_SRAM_MAX] = {
   
3.       {LP4_DDR3200 /*0*/, DIV8_MODE, SRAM_SHU1, DUTY_LAST_K,  VREF_CALI_OFF,  CLOSE_LOOP_MODE},  // highest freq of term group (3733) must k first.
   
4.       {LP4_DDR3200 /*1*/, DIV8_MODE, SRAM_SHU0, DUTY_NEED_K,  VREF_CALI_ON,   CLOSE_LOOP_MODE},  // highest freq of term group (3733) must k first.
   
5. ......
   
6. 
   
7. }

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