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Subject[PATCH v1 04/63] Input: atmel_mxt_ts - split large i2c transfers into blocks
Date
From: Nick Dyer <nick.dyer@itdev.co.uk>

On some firmware variants, the size of the info block exceeds what can
be read in a single transfer.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
(cherry picked from ndyer/linux/for-upstream commit 74c4f5277cfa403d43fafc404119dc57a08677db)
[gdavis: Forward port and fix conflicts due to v4.14.51 commit
960fe000b1d3 ("Input: atmel_mxt_ts - fix the firmware
update").]
Signed-off-by: George G. Davis <george_davis@mentor.com>
Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
---
drivers/input/touchscreen/atmel_mxt_ts.c | 27 +++++++++++++++++++++---
1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index 9b165d23e092..2d70ddf71cd9 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -40,7 +40,7 @@
#define MXT_OBJECT_START 0x07
#define MXT_OBJECT_SIZE 6
#define MXT_INFO_CHECKSUM_SIZE 3
-#define MXT_MAX_BLOCK_WRITE 256
+#define MXT_MAX_BLOCK_WRITE 255

/* Object types */
#define MXT_DEBUG_DIAGNOSTIC_T37 37
@@ -659,6 +659,27 @@ static int __mxt_read_reg(struct i2c_client *client,
return ret;
}

+static int mxt_read_blks(struct mxt_data *data, u16 start, u16 count, u8 *buf)
+{
+ u16 offset = 0;
+ int error;
+ u16 size;
+
+ while (offset < count) {
+ size = min(MXT_MAX_BLOCK_WRITE, count - offset);
+
+ error = __mxt_read_reg(data->client,
+ start + offset,
+ size, buf + offset);
+ if (error)
+ return error;
+
+ offset += size;
+ }
+
+ return 0;
+}
+
static int __mxt_write_reg(struct i2c_client *client, u16 reg, u16 len,
const void *val)
{
@@ -1793,7 +1814,7 @@ static int mxt_read_info_block(struct mxt_data *data)
id_buf = buf;

/* Read rest of info block */
- error = __mxt_read_reg(client, MXT_OBJECT_START,
+ error = mxt_read_blks(data, MXT_OBJECT_START,
size - MXT_OBJECT_START,
id_buf + MXT_OBJECT_START);
if (error)
@@ -2783,7 +2804,7 @@ static ssize_t mxt_object_show(struct device *dev,
u16 size = mxt_obj_size(object);
u16 addr = object->start_address + j * size;

- error = __mxt_read_reg(data->client, addr, size, obuf);
+ error = mxt_read_blks(data, addr, size, obuf);
if (error)
goto done;

--
2.19.2
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