542396750@qq.com 说：他这个cs接地了，我这边死活不显示，把cs与cs连接后，秒出。
cs不能直接接地，言外之意就是cs信号有时用来表示一次通讯的开始。典型的就是spi flash片选接地导致无法通信。
@tlxfif
这两个都是配置rgb lcd的，你如果用fbtft里的驱动这个可以删了，lg,lb070wv8这个是一个5寸的lcd，驱动文件位于drivers\gpu\drm\panel\panel.simple.c
这是lcd的参数
static const struct drm_display_mode lg_lb070wv8_mode = {
.clock = 33246,
.hdisplay = 800,
.hsync_start = 800 + 88,
.hsync_end = 800 + 88 + 80,
.htotal = 800 + 88 + 80 + 88,
.vdisplay = 480,
.vsync_start = 480 + 10,
.vsync_end = 480 + 10 + 25,
.vtotal = 480 + 10 + 25 + 10,
};
static const struct panel_desc lg_lb070wv8 = {
.modes = &lg_lb070wv8_mode,
.num_modes = 1,
.bpc = 8,
.size = {
.width = 151,
.height = 91,
},
.bus_format = MEDIA_BUS_FMT_RGB888_1X7X4_SPWG,
.connector_type = DRM_MODE_CONNECTOR_LVDS,
};今天也遇到这个问题了，高速卡低速卡都不行，现在正在试下降低时钟和data bit。
[ 1454.703001] mmc0: host does not support reading read-only switch, assuming write-enable
[ 1454.713272] mmc0: new high speed SDHC card at address 1234
[ 1454.721075] mmcblk0: mmc0:1234 SA04G 3.68 GiB
[ 1454.728666] sunxi-mmc 1c0f000.mmc: data error, sending stop command
[ 1454.735066] mmcblk0: timed out sending r/w cmd command, card status 0x900
[ 1454.830585] sunxi-mmc 1c0f000.mmc: data error, sending stop command
[ 1454.837049] mmcblk0: timed out sending r/w cmd command, card status 0x900
[ 1454.843849] print_req_error: I/O error, dev mmcblk0, sector 0
[ 1454.849686] Buffer I/O error on dev mmcblk0, logical block 0, async page read
[ 1454.859522] sunxi-mmc 1c0f000.mmc: data error, sending stop command
[ 1454.866016] mmcblk0: timed out sending r/w cmd command, card status 0x900
[ 1454.872816] print_req_error: I/O error, dev mmcblk0, sector 0
[ 1454.878659] Buffer I/O error on dev mmcblk0, logical block 0, async page read
[ 1454.886780] mmcblk0: unable to read partition table之前在这个帖子中谈到使用国产flash芯片xt25f128的荔枝nano板子
[求助]荔枝派nano uboot卡在SF: unrecognized JEDEC id bytes: 0b, 40, 18
出现了一个很奇怪的问题就是在源码上做了更改，编译之后通过sunxi-fel烧写到flash上并不生效。修改flash id数组后无效 我以为是u-boot中spi driver这些跟驱动注册相关的问题，但是问题远比我想象的要简单。
我为了方便烧写flash将其1 4脚用拨片式开关连接了起来，需要进入fel模式的时候闭合开关。这个细节导致了我后来在源码上所做的修改都不生效，包括一开始修改的flash id。
闭合开关会导致CS#被拉低，导致芯片无法控制cs引脚片选，从而使得指令无法执行。算是自己给自己挖了个坑吧。。。
不过奇怪的是，sunxi-fel烧写时没出现异常，烧写速度也是浮动的，给我造成了一种正在烧写的假象:(
U-Boot SPL 2018.01-05676-g00188782ee-dirty (May 19 2018 - 15:47:49)
DRAM: 32 MiB
SPL: Unsupported Boot Device!
Trying to boot from sunxi SPI
U-Boot 2018.01-05676-g00188782ee-dirty (May 19 2018 - 15:47:49 +0800) Allwinner Technology
CPU: Allwinner F Series (SUNIV)
Model: Lichee Pi Nano
DRAM: 32 MiB
Using default environment
Setting up a 800x480 lcd console (overscan 0x0)
In: serial@1c25000
Out: serial@1c25000
Err: serial@1c25000
Net: No ethernet found.
starting USB...
No controllers found
Hit any key to stop autoboot: 0
SF: unrecognized JEDEC id bytes: 0b, 40, 18
Failed to initialize SPI flash at 0:0 (error -2)
No SPI flash selected. Please run `sf probe'
No SPI flash selected. Please run `sf probe'
=>