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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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