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chendong

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注册时间： 2019-07-22

已发帖子： 93

积分： 94

v3s i2c 写地址

大家好最近弄v3s 的i2c ，发现在内核对从地址是这么处理的
/ 7-1bits addr, xxxx_xxx0 /
addr = (i2c->msg[i2c->msg_idx].addr & 0x7f) << 1;
，这要是我的从地址是0x70 , 写的时候变成了0xe0, 没法控制设备啊。我把地址强制成0x70，就可以了，这什么意思？这驱动有问题？按理说不应该啊。

static void sunxi_i2c_addr_byte(struct sunxi_i2c *i2c)
{
unsigned char addr = 0;
unsigned char tmp = 0;

if (i2c->msg[i2c->msg_idx].flags & I2C_M_TEN) {
/ 0111_10xx,ten bits address--9:8bits /
tmp = 0x78 | ( ( (i2c->msg[i2c->msg_idx].addr)>>8 ) & 0x03);
addr = tmp << 1;//1111_0xx0
/ how about the second part of ten bits addr? Answer: deal at twi_core_process() /
}
else {
/ 7-1bits addr, xxxx_xxx0 /
addr = (i2c->msg[i2c->msg_idx].addr & 0x7f) << 1;
}

/ read, default value is write /
if (i2c->msg[i2c->msg_idx].flags & I2C_M_RD) {
addr |= 1;
}