why USB hid Disable DCache to run?

[1920844004]

SCB_DisableDCache(); 

i must use this code ,USB HID can run,if  Comment out ,USB HID CAN NOT   enumeration .

why? who can help me ?

*.scf is：

RW_m_data m_data_start m_data_size-Stack_Size-Heap_Size { ; RW data
.ANY (+RW +ZI)
*(m_usb_dma_init_data)
*(m_usb_dma_noninit_data)
}

RW_m_ncache m_ncache_start m_ncache_size { ; ncache RW data
* (NonCacheable.init)
* (NonCacheable)
}

[igorpadykov]

Hi zhihui

for explanation one can refer to comments from attached board.c

usb_host_hid_generic example:

void BOARD_ConfigMPU(void)
..
Above are normal use settings, if your want to see more details or want to
config different inner/outter cache policy.      
Please refer to Table 4-55 /4-56 in arm cortex-M7 generic user guide <dui0646b_cortex_m7_dgug.pdf>

Best regards
igor
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