From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-da0-f51.google.com (mail-da0-f51.google.com [209.85.210.51]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 8C0A22C008A for ; Mon, 26 Nov 2012 09:19:58 +1100 (EST) Received: by mail-da0-f51.google.com with SMTP id i30so2714119dad.38 for ; Sun, 25 Nov 2012 14:19:55 -0800 (PST) From: sachin.surendran@gmail.com To: galak@kernel.crashing.org, jochen@scram.de Subject: [PATCH 1/1] i2c-cpm: Fix to takeback i2c bus master-ship after a collision Date: Mon, 26 Nov 2012 11:20:01 +1300 Message-Id: <1353882001-30744-1-git-send-email-sachin.surendran@gmail.com> In-Reply-To: References: Cc: Sachin Surendran , sachin.surendran@gmail.com, linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Sachin Surendran In case of collision on i2c bus the controller which lost bus mastership stays as a slave for all subsequent transfers. This results in the i2c controller never writing to the bus for future transactions, resulting in i2c transfer timeouts. This fix checks for a collision on last I2C transaction and sets the I2COM_MASTER bit for the new transaction. Signed-off-by: Sachin Surendran --- drivers/i2c/busses/i2c-cpm.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/i2c/busses/i2c-cpm.c b/drivers/i2c/busses/i2c-cpm.c index c1e1096..bb94c6d 100644 --- a/drivers/i2c/busses/i2c-cpm.c +++ b/drivers/i2c/busses/i2c-cpm.c @@ -338,6 +338,14 @@ static int cpm_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) tptr = 0; rptr = 0; + /* + * If there was a collision in the last i2c transaction, + * Set I2COM_MASTER as it was cleared during collision. + */ + if (in_be16(&tbdf->cbd_sc) & BD_SC_CL) { + out_8(&cpm->i2c_reg->i2com, I2COM_MASTER); + } + while (tptr < num) { pmsg = &msgs[tptr]; dev_dbg(&adap->dev, "R: %d T: %d\n", rptr, tptr); -- 1.7.9.5