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Subject[PATCH v9 04/55] 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>
[jiada: Change mxt_read_blks() to __mxt_read_reg(), original __mxt_read_reg() to
__mxt_read_chunk()]
Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
---
drivers/input/touchscreen/atmel_mxt_ts.c | 28 +++++++++++++++++++++---
1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index 3f1ebe14802f..7e6a66e3e1e0 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
@@ -624,8 +624,8 @@ static int mxt_send_bootloader_cmd(struct mxt_data *data, bool unlock)
return 0;
}

-static int __mxt_read_reg(struct i2c_client *client,
- u16 reg, u16 len, void *val)
+static int __mxt_read_chunk(struct i2c_client *client,
+ u16 reg, u16 len, void *val)
{
struct i2c_msg xfer[2];
u8 buf[2];
@@ -659,6 +659,28 @@ static int __mxt_read_reg(struct i2c_client *client,
return ret;
}

+static int __mxt_read_reg(struct i2c_client *client,
+ u16 reg, u16 len, void *buf)
+{
+ u16 offset = 0;
+ int error;
+ u16 size;
+
+ while (offset < len) {
+ size = min(MXT_MAX_BLOCK_WRITE, len - offset);
+
+ error = __mxt_read_chunk(client,
+ reg + 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)
{
--
2.17.1
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