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Subject[PATCH v2] Input: elants_i2c - Use DMA safe i2c when possible
Date
This irq handler is always reading bytes from the device into a
kmalloced buffer, so it's safe to mark this transaction as DMA safe.
This avoids bouncing the buffer when an i2c controller decides to use
DMA for a transaction.

Cc: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
---

Changes from v1:
* Moved buf to end of structure to keep it cacheline aligned and DMA
safe

drivers/input/touchscreen/elants_i2c.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/input/touchscreen/elants_i2c.c b/drivers/input/touchscreen/elants_i2c.c
index d21ca39b0fdb..f2cb23121833 100644
--- a/drivers/input/touchscreen/elants_i2c.c
+++ b/drivers/input/touchscreen/elants_i2c.c
@@ -147,10 +147,11 @@ struct elants_data {
u8 cmd_resp[HEADER_SIZE];
struct completion cmd_done;

- u8 buf[MAX_PACKET_SIZE];
-
bool wake_irq_enabled;
bool keep_power_in_suspend;
+
+ /* Must be last to be used for DMA operations */
+ u8 buf[MAX_PACKET_SIZE] ____cacheline_aligned;
};

static int elants_i2c_send(struct i2c_client *client,
@@ -863,7 +864,7 @@ static irqreturn_t elants_i2c_irq(int irq, void *_dev)
int i;
int len;

- len = i2c_master_recv(client, ts->buf, sizeof(ts->buf));
+ len = i2c_master_recv_dmasafe(client, ts->buf, sizeof(ts->buf));
if (len < 0) {
dev_err(&client->dev, "%s: failed to read data: %d\n",
__func__, len);
--
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