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Commit 0c25aefa authored by Joakim Tjernlund's avatar Joakim Tjernlund Committed by Wolfram Sang
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i2c: mpc: Wait for STOP to hit the bus 



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: default avatarJoakim Tjernlund <Joakim.Tjernlund@transmode.se>
Signed-off-by: default avatarWolfram Sang <w.sang@pengutronix.de>
parent 2bdbfa9c

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;

}