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authorWolfram Sang <wsa+renesas@sang-engineering.com>2015-01-29 18:33:16 +0100
committerWolfram Sang <wsa@the-dreams.de>2015-01-30 17:58:43 +0100
commit32e224090fa310a58fdb47049caf631272ceb044 (patch)
tree09d15847c50950c5125a2b05ddaa3a683dcb3a3c
parentd5fd120e7860c2b3d4c936a2ebadb6b244bec4c8 (diff)
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i2c: sh_mobile: terminate DMA reads properly
DMA read requests could miss proper termination, so two more bytes would have been read via PIO overwriting the end of the buffer with wrong data. Make DMA stop handling more readable while we are here. Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
-rw-r--r--drivers/i2c/busses/i2c-sh_mobile.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2c-sh_mobile.c
index 440d5dbc8b5f..007818b3e174 100644
--- a/drivers/i2c/busses/i2c-sh_mobile.c
+++ b/drivers/i2c/busses/i2c-sh_mobile.c
@@ -139,6 +139,7 @@ struct sh_mobile_i2c_data {
int pos;
int sr;
bool send_stop;
+ bool stop_after_dma;
struct resource *res;
struct dma_chan *dma_tx;
@@ -407,7 +408,7 @@ static int sh_mobile_i2c_isr_tx(struct sh_mobile_i2c_data *pd)
if (pd->pos == pd->msg->len) {
/* Send stop if we haven't yet (DMA case) */
- if (pd->send_stop && (iic_rd(pd, ICCR) & ICCR_BBSY))
+ if (pd->send_stop && pd->stop_after_dma)
i2c_op(pd, OP_TX_STOP, 0);
return 1;
}
@@ -449,6 +450,13 @@ static int sh_mobile_i2c_isr_rx(struct sh_mobile_i2c_data *pd)
real_pos = pd->pos - 2;
if (pd->pos == pd->msg->len) {
+ if (pd->stop_after_dma) {
+ /* Simulate PIO end condition after DMA transfer */
+ i2c_op(pd, OP_RX_STOP, 0);
+ pd->pos++;
+ break;
+ }
+
if (real_pos < 0) {
i2c_op(pd, OP_RX_STOP, 0);
break;
@@ -536,6 +544,7 @@ static void sh_mobile_i2c_dma_callback(void *data)
sh_mobile_i2c_dma_unmap(pd);
pd->pos = pd->msg->len;
+ pd->stop_after_dma = true;
iic_set_clr(pd, ICIC, 0, ICIC_TDMAE | ICIC_RDMAE);
}
@@ -726,6 +735,7 @@ static int sh_mobile_i2c_xfer(struct i2c_adapter *adapter,
bool do_start = pd->send_stop || !i;
msg = &msgs[i];
pd->send_stop = i == num - 1 || msg->flags & I2C_M_STOP;
+ pd->stop_after_dma = false;
err = start_ch(pd, msg, do_start);
if (err)