From: Andrew Jackson <Andrew.Jackson@arm.com>
To: Wolfram Sang <wsa@the-dreams.de>,
Andrew Morton <akpm@linux-foundation.org>,
Baruch Siach <baruch@tkos.co.il>,
"Du, Wenkai" <wenkai.du@intel.com>,
Shinya Kuribayashi <skuribay@pobox.com>,
Romain Baeriswyl <Romain.Baeriswyl@abilis.com>,
linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Liviu Dudau <Liviu.Dudau@arm.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: [PATCH] i2c: designware: prevent early stop on TX FIFO empty
Date: Fri, 07 Nov 2014 12:10:44 +0000 [thread overview]
Message-ID: <545CB6C4.8010201@arm.com> (raw)
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 <Andrew.Jackson@arm.com>
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
---
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
next reply other threads:[~2014-11-07 12:12 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-07 12:10 Andrew Jackson [this message]
2014-11-19 9:21 ` [PATCH] i2c: designware: prevent early stop on TX FIFO empty Wolfram Sang
2014-11-19 13:35 ` Baruch Siach
2014-11-19 14:18 ` Mika Westerberg
2014-11-21 7:05 ` Wolfram Sang
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