From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Jackson Subject: [PATCH] i2c: designware: prevent early stop on TX FIFO empty Date: Fri, 07 Nov 2014 12:10:44 +0000 Message-ID: <545CB6C4.8010201@arm.com> 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Wolfram Sang , Andrew Morton , Baruch Siach , "Du, Wenkai" , Shinya Kuribayashi , Romain Baeriswyl , linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Liviu Dudau , "linux-arm-kernel@lists.infradead.org" List-Id: linux-i2c@vger.kernel.org If the Designware core is configured with IC_EMPTYFIFO_HOLD_MASTER_EN set to zero, allowing the TX FIFO to become empty causes a STOP condition to be generated on the I2C bus. If the transmit FIFO threshold is set too high, an erroneous STOP condition can be generated on long transfers - particularly where the interrupt latency is extended. Signed-off-by: Andrew Jackson Signed-off-by: Liviu Dudau --- drivers/i2c/busses/i2c-designware-core.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c index 3c20e4b..e070edd 100644 --- a/drivers/i2c/busses/i2c-designware-core.c +++ b/drivers/i2c/busses/i2c-designware-core.c @@ -363,7 +363,7 @@ int i2c_dw_init(struct dw_i2c_dev *dev) } /* Configure Tx/Rx FIFO threshold levels */ - dw_writel(dev, dev->tx_fifo_depth - 1, DW_IC_TX_TL); + dw_writel(dev, dev->tx_fifo_depth / 2, DW_IC_TX_TL); dw_writel(dev, 0, DW_IC_RX_TL); /* configure the i2c master */ -- 1.7.1