From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joakim Tjernlund Subject: [PATCH] i2c-mpc: Wait for STOP to hit the bus Date: Thu, 30 Aug 2012 12:40:04 +0200 Message-ID: <1346323204-19210-1-git-send-email-Joakim.Tjernlund@transmode.se> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+glppe-linuxppc-embedded-2=m.gmane.org@lists.ozlabs.org Sender: "Linuxppc-dev" To: linux-i2c@vger.kernel.org, linuxppc-dev@lists.ozlabs.org List-Id: linux-i2c@vger.kernel.org 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 --- drivers/i2c/busses/i2c-mpc.c | 18 +++++++++++++++++- 1 files changed, 17 insertions(+), 1 deletions(-) diff --git drivers/i2c/busses/i2c-mpc.c drivers/i2c/busses/i2c-mpc.c index 3d31879..c08f287 100644 --- drivers/i2c/busses/i2c-mpc.c +++ drivers/i2c/busses/i2c-mpc.c @@ -574,7 +574,23 @@ 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; } -- 1.7.8.6