From: Matthias Schiffer matthias.schiffer@ew.tq-group.com
[ Upstream commit 5190417bdf72c71b65bd9892103c6186816a6e8b ]
We found that after commit 9c46929e7989 ("ARM: implement THREAD_INFO_IN_TASK for uniprocessor systems"), the PCF85063 RTC driver stopped working on i.MX28 due to regmap_bulk_read() reading bogus data into a stack buffer. This is caused by the i2c-mxs driver using DMA transfers even for messages without the I2C_M_DMA_SAFE flag, and the aforementioned commit enabling vmapped stacks.
As the MXS I2C controller requires DMA for reads of >4 bytes, DMA can't be disabled, so the issue is fixed by using i2c_get_dma_safe_msg_buf() to create a bounce buffer when needed.
Fixes: 9c46929e7989 ("ARM: implement THREAD_INFO_IN_TASK for uniprocessor systems") Signed-off-by: Matthias Schiffer matthias.schiffer@ew.tq-group.com Signed-off-by: Wolfram Sang wsa@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/i2c/busses/i2c-mxs.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-)
diff --git a/drivers/i2c/busses/i2c-mxs.c b/drivers/i2c/busses/i2c-mxs.c index d113bed795452..e0f3b3545cfe4 100644 --- a/drivers/i2c/busses/i2c-mxs.c +++ b/drivers/i2c/busses/i2c-mxs.c @@ -171,7 +171,7 @@ static void mxs_i2c_dma_irq_callback(void *param) }
static int mxs_i2c_dma_setup_xfer(struct i2c_adapter *adap, - struct i2c_msg *msg, uint32_t flags) + struct i2c_msg *msg, u8 *buf, uint32_t flags) { struct dma_async_tx_descriptor *desc; struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap); @@ -226,7 +226,7 @@ static int mxs_i2c_dma_setup_xfer(struct i2c_adapter *adap, }
/* Queue the DMA data transfer. */ - sg_init_one(&i2c->sg_io[1], msg->buf, msg->len); + sg_init_one(&i2c->sg_io[1], buf, msg->len); dma_map_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE); desc = dmaengine_prep_slave_sg(i2c->dmach, &i2c->sg_io[1], 1, DMA_DEV_TO_MEM, @@ -259,7 +259,7 @@ static int mxs_i2c_dma_setup_xfer(struct i2c_adapter *adap, /* Queue the DMA data transfer. */ sg_init_table(i2c->sg_io, 2); sg_set_buf(&i2c->sg_io[0], &i2c->addr_data, 1); - sg_set_buf(&i2c->sg_io[1], msg->buf, msg->len); + sg_set_buf(&i2c->sg_io[1], buf, msg->len); dma_map_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE); desc = dmaengine_prep_slave_sg(i2c->dmach, i2c->sg_io, 2, DMA_MEM_TO_DEV, @@ -563,6 +563,7 @@ static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap); int ret; int flags; + u8 *dma_buf; int use_pio = 0; unsigned long time_left;
@@ -588,13 +589,20 @@ static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, if (ret && (ret != -ENXIO)) mxs_i2c_reset(i2c); } else { + dma_buf = i2c_get_dma_safe_msg_buf(msg, 1); + if (!dma_buf) + return -ENOMEM; + reinit_completion(&i2c->cmd_complete); - ret = mxs_i2c_dma_setup_xfer(adap, msg, flags); - if (ret) + ret = mxs_i2c_dma_setup_xfer(adap, msg, dma_buf, flags); + if (ret) { + i2c_put_dma_safe_msg_buf(dma_buf, msg, false); return ret; + }
time_left = wait_for_completion_timeout(&i2c->cmd_complete, msecs_to_jiffies(1000)); + i2c_put_dma_safe_msg_buf(dma_buf, msg, true); if (!time_left) goto timeout;