[v11,04/56] Input: atmel_mxt_ts - split large i2c transfers into blocks

Commit Message

Wang, Jiada May 8, 2020, 5:56 a.m. UTC

From: Nick Dyer <[e-mail]>

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

Signed-off-by: Nick Dyer <[e-mail]>
(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 <[e-mail]>
[jiada: Change mxt_read_blks() to __mxt_read_reg(), original __mxt_read_reg() to
	__mxt_read_chunk()]
Signed-off-by: Jiada Wang <[e-mail]>
---
 drivers/input/touchscreen/atmel_mxt_ts.c | 28 +++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

Comments

Dmitry Torokhov May 11, 2020, 10:19 p.m. UTC | #1

Hi Jiada, Nick,

On Thu, May 07, 2020 at 10:56:04PM -0700, Jiada Wang wrote:
> From: Nick Dyer <[e-mail]>
> 
> On some firmware variants, the size of the info block exceeds what can
> be read in a single transfer.

Is this limitation of the mXT controller or maybe it is issue with
implementation of the particular i2c adapter and should be dealt with
there?

Thanks.

Wang, Jiada June 30, 2020, 2:33 p.m. UTC | #2

Hello Dmitry

On 2020/05/12 7:19, Dmitry Torokhov wrote:
> Hi Jiada, Nick,
> 
> On Thu, May 07, 2020 at 10:56:04PM -0700, Jiada Wang wrote:
>> From: Nick Dyer <[e-mail]>
>>
>> On some firmware variants, the size of the info block exceeds what can
>> be read in a single transfer.
> 
> Is this limitation of the mXT controller or maybe it is issue with
> implementation of the particular i2c adapter and should be dealt with
> there?
> 
This patch was authored by Nick,
but I assume it is trying to address issue due to I2C adapter limitation
which following patch in this series is already doing
"Input: atmel_mxt_ts: Limit the max bytes transferred in an i2c transaction"

I will extend patch "Input: atmel_mxt_ts: Limit the max bytes 
transferred in an i2c transaction"
to also cover this case.

Thanks,
Jiada

> Thanks.
>

Patch

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)
 {