fbtft and netboot

hi all
i have an orange-pi zero that boots from network. the kernel and some other files are loaded over TFTP and the root path is mounted by NFS and every thing works fine.
also i have a 3.5 inches LCD that works with fbtft_device module.
the problem is when the board boots over network, the LCD dose not initialize completely but when i boot the board by SD card the LCD init's 100% fine.

there are no error in dmesg but the LCD is 1/3 black and 2/3 white.
dmesg:
[   51.270008] fbtft_device:  SPI devices registered:
[   51.270303] fbtft_device:      spidev spi0.0 33000kHz 8 bits mode=0x00
[   51.270362] fbtft_device:      spidev spi1.0 33000kHz 8 bits mode=0x00
[   51.270413] fbtft_device:  'fb' Platform devices registered:
[   51.271544] fbtft_device: Deleting spi1.0
[   51.273154] fbtft_device:  GPIOS used by 'fb_ili9486':
[   51.273204] fbtft_device:    'dc' = GPIO18
[   51.273238] fbtft_device:    'reset' = GPIO2
[   51.273272] fbtft_device:  SPI devices registered:
[   51.273318] fbtft_device:      spidev spi0.0 33000kHz 8 bits mode=0x00
[   51.273368] fbtft_device:      fb_ili9486 spi1.0 8000kHz 8 bits mode=0x00