i2c: mpc: Wait for STOP to hit the bus (0c25aefa) · Commits · 戴 / test

mpc_i2c_stop() only initiates STOP but does not wait for it to hit the I2C bus. This is a problem when using I2C devices which uses fairly long clock stretching just before STOP if you also have an i2c-mux which may switch to another bus before STOP has been processed. Signed-off-by:

Joakim Tjernlund <Joakim.Tjernlund@transmode.se> Signed-off-by:

Wolfram Sang <w.sang@pengutronix.de>

drivers/i2c/busses/i2c-mpc.c

+17 −1

Original line number	Diff line number	Diff line
		@@ -576,7 +576,23 @@ static int mpc_xfer(struct i2c_adapter adap, struct i2c_msg msgs, int num)
		mpc_write(i2c, pmsg->addr, pmsg->buf, pmsg->len, i);
		}
		}
		mpc_i2c_stop(i2c);
		mpc_i2c_stop(i2c); /* Initiate STOP */
		orig_jiffies = jiffies;
		/* Wait until STOP is seen, allow up to 1 s */
		while (readb(i2c->base + MPC_I2C_SR) & CSR_MBB) {
		if (time_after(jiffies, orig_jiffies + HZ)) {
		u8 status = readb(i2c->base + MPC_I2C_SR);

		dev_dbg(i2c->dev, "timeout\n");
		if ((status & (CSR_MCF \| CSR_MBB \| CSR_RXAK)) != 0) {
		writeb(status & ~CSR_MAL,
		i2c->base + MPC_I2C_SR);
		mpc_i2c_fixup(i2c);
		}
		return -EIO;
		}
		cond_resched();
		}
		return (ret < 0) ? ret : num;
		}

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