@@ -414,8 +414,14 @@ i2c_dw_xfer_msg(struct dw_i2c_dev *dev)
while (buf_len > 0 && tx_limit > 0 && rx_limit > 0) {
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, 0x100, DW_IC_DATA_CMD);
rx_limit--;
+ dev->rx_outstanding++;
} else
dw_writel(dev, *buf++, DW_IC_DATA_CMD);
tx_limit--; buf_len--;
@@ -468,8 +474,10 @@ 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;
@@ -527,6 +535,7 @@ 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)
@@ -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
This is a note to let you know that I have just added a patch titled i2c: designware: fix RX FIFO overrun to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue This patch is scheduled to be released in version 3.8.13.2. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.8.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From b4a2ace48a3f4bc7b537050ce050b51de1875dbc Mon Sep 17 00:00:00 2001 From: Josef Ahmad <josef.ahmad@linux.intel.com> Date: Fri, 19 Apr 2013 17:28:10 +0100 Subject: i2c: designware: fix RX FIFO overrun commit e6f34cea56f5b95498070eaa9f4aa3ba4a9e4f62 upstream. 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> [ kamal: backport to 3.8 ] Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/i2c/busses/i2c-designware-core.c | 11 ++++++++++- drivers/i2c/busses/i2c-designware-core.h | 2 ++ 2 files changed, 12 insertions(+), 1 deletion(-) -- 1.8.1.2