TI中文支持网用AM3352的板子，内核4.19，emmc1 不能使能8线
我看了很多贴子的log似乎都用的4线 驱动omap_hsmmc.c
&mmc2 {
vmmc-supply = <&vmmcsd_fixed>;
pinctrl-names = "default";
pinctrl-0 = <&emmc_pins>;
bus-width = <8>;
status = "okay";
ti,non-removable;
};
信息：
root:~# cat /sys/kernel/debug/mmc1/ios
clock: 52000000 Hz
vdd: 20 (3.2 ~ 3.3 V)
bus mode: 2 (push-pull)
chip select: 0 (don't care)
power mode: 2 (on)
bus width: 2 (4 bits)
timing spec: 1 (mmc high-speed)
log：
[ 1.662924] omap_i2c 44e0b000.i2c: bus 0 rev0.11 at 100 kHz
[ 1.672359] omap_hsmmc 481d8000.mmc: omap_hsmmc_set_bus_width ios->timing=1 ios->bus_width=0
[ 1.680990] omap_hsmmc 481d8000.mmc: Set clock to 400000Hz
[ 1.686838] omap_hsmmc 481d8000.mmc: omap_hsmmc_set_bus_width ios->timing=1 ios->bus_width=0
[ 1.695431] omap_hsmmc 481d8000.mmc: Set clock to 52000000Hz
[ 1.701433] omap_hsmmc 481d8000.mmc: omap_hsmmc_set_bus_width ios->timing=1 ios->bus_width=3
[ 1.710020] omap_hsmmc 481d8000.mmc: Set clock to 52000000Hz
[ 1.716069] mmc1: switch to bus width 8 faiLED
[ 1.720589] omap_hsmmc 481d8000.mmc: omap_hsmmc_set_bus_width ios->timing=1 ios->bus_width=2
[ 1.729175] omap_hsmmc 481d8000.mmc: Set clock to 52000000Hz
[ 1.735710] mmc1: new high speed MMC card at address 0001
[ 1.742154] mmcblk1: mmc1:0001 004G60 3.69 GiB
[ 1.747295] mmcblk1boot0: mmc1:0001 004G60 partition 1 2.00 MiB
[ 1.753768] mmcblk1boot1: mmc1:0001 004G60 partition 2 2.00 MiB
[ 1.759963] mmcblk1rpmb: mmc1:0001 004G60 partition 3 512 KiB, chardev (244:0)
Nancy Wang：
am335x BBB板就是8bit EMMC，BBB的dts文件配置的bus width也是8bit，建议参考看一下。
user5759638：
回复 Nancy Wang:
你确认BBB板子 的emmc版本是5.1或者大于4.5以上。这个问题说是 V4.41是OK的。
Nancy Wang：
回复 user5759638:
是4.5。
user5759638：
回复 Nancy Wang:
你用过dd命令 测过没有速度大概多少啊。我测出来大约20M/S
echo 3 > /proc/sys/vm/drop_caches
time dd if=/dev/block/mmcblk1 of=/dev/null bs=16k count=65536
