2020-05-08 06:03:54

by Jiada Wang

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

From: Nick Dyer <[email protected]>

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

Signed-off-by: Nick Dyer <[email protected]>
(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 <[email protected]>
[jiada: Change mxt_read_blks() to __mxt_read_reg(), original __mxt_read_reg() to
__mxt_read_chunk()]
Signed-off-by: Jiada Wang <[email protected]>
---
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

2020-05-11 22:21:47

by Dmitry Torokhov

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

Hi Jiada, Nick,

On Thu, May 07, 2020 at 10:56:04PM -0700, Jiada Wang wrote:
> From: Nick Dyer <[email protected]>
>
> 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.

--
Dmitry

2020-06-30 14:34:16

by Jiada Wang

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

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 <[email protected]>
>>
>> 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.
>