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authorJosef Ahmad <josef.ahmad@linux.intel.com>2013-04-19 17:28:10 +0100
committerWolfram Sang <wsa@the-dreams.de>2013-05-17 10:33:11 +0200
commite6f34cea56f5b95498070eaa9f4aa3ba4a9e4f62 (patch)
treee3b50a4ea7df97b564811788585759b2ae410dec /drivers/i2c/busses
parentf722406faae2d073cc1d01063d1123c35425939e (diff)
downloadvexpress-lsk-e6f34cea56f5b95498070eaa9f4aa3ba4a9e4f62.tar.gz
i2c: designware: fix RX FIFO overrun
i2c_dw_xfer_msg() pushes a number of bytes to transmit/receive to/from the bus into the TX FIFO. For master-rx transactions, the maximum amount of data that can be received is calculated depending solely on TX and RX FIFO load. This is racy - TX FIFO may contain master-rx data yet to be processed, which will eventually land into the RX FIFO. This data is not taken into account and the function may request more data than the controller is actually capable of storing. This patch ensures the driver takes into account the outstanding master-rx data in TX FIFO to prevent RX FIFO overrun. Signed-off-by: Josef Ahmad <josef.ahmad@linux.intel.com> Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de> Cc: stable@kernel.org
Diffstat (limited to 'drivers/i2c/busses')
-rw-r--r--drivers/i2c/busses/i2c-designware-core.c11
-rw-r--r--drivers/i2c/busses/i2c-designware-core.h2
2 files changed, 12 insertions, 1 deletions
diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index 21fbb340ad6..1f06c8e9934 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -448,8 +448,14 @@ i2c_dw_xfer_msg(struct dw_i2c_dev *dev)
cmd |= BIT(9);
if (msgs[dev->msg_write_idx].flags & I2C_M_RD) {
+
+ /* avoid rx buffer overrun */
+ if (rx_limit - dev->rx_outstanding <= 0)
+ break;
+
dw_writel(dev, cmd | 0x100, DW_IC_DATA_CMD);
rx_limit--;
+ dev->rx_outstanding++;
} else
dw_writel(dev, cmd | *buf++, DW_IC_DATA_CMD);
tx_limit--; buf_len--;
@@ -502,8 +508,10 @@ i2c_dw_read(struct dw_i2c_dev *dev)
rx_valid = dw_readl(dev, DW_IC_RXFLR);
- for (; len > 0 && rx_valid > 0; len--, rx_valid--)
+ for (; len > 0 && rx_valid > 0; len--, rx_valid--) {
*buf++ = dw_readl(dev, DW_IC_DATA_CMD);
+ dev->rx_outstanding--;
+ }
if (len > 0) {
dev->status |= STATUS_READ_IN_PROGRESS;
@@ -561,6 +569,7 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
dev->msg_err = 0;
dev->status = STATUS_IDLE;
dev->abort_source = 0;
+ dev->rx_outstanding = 0;
ret = i2c_dw_wait_bus_not_busy(dev);
if (ret < 0)
diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 9c1840ee09c..e761ad18dd6 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -60,6 +60,7 @@
* @adapter: i2c subsystem adapter node
* @tx_fifo_depth: depth of the hardware tx fifo
* @rx_fifo_depth: depth of the hardware rx fifo
+ * @rx_outstanding: current master-rx elements in tx fifo
*/
struct dw_i2c_dev {
struct device *dev;
@@ -88,6 +89,7 @@ struct dw_i2c_dev {
u32 master_cfg;
unsigned int tx_fifo_depth;
unsigned int rx_fifo_depth;
+ int rx_outstanding;
};
#define ACCESS_SWAP 0x00000001