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    Subject[PATCH 2/4] power: bq20z75: add i2c retry mechanism
    Date
    From: Rhyland Klein <rklein@nvidia.com>

    With the support of platform data, now adding support for option i2c retries
    on read/write failures. Ths is specified through the optional platform data.

    Signed-off-by: Rhyland Klein <rklein@nvidia.com>
    ---
    drivers/power/bq20z75.c | 37 +++++++++++++++++++++++++++++++------
    include/linux/power/bq20z75.h | 2 ++
    2 files changed, 33 insertions(+), 6 deletions(-)

    diff --git a/drivers/power/bq20z75.c b/drivers/power/bq20z75.c
    index a51e98d..e82d10e 100644
    --- a/drivers/power/bq20z75.c
    +++ b/drivers/power/bq20z75.c
    @@ -156,30 +156,55 @@ struct bq20z75_info {

    static int bq20z75_read_word_data(struct i2c_client *client, u8 address)
    {
    - s32 ret;
    + struct bq20z75_info *bq20z75_device = i2c_get_clientdata(client);
    + s32 ret = 0;
    + int retries = 1;
    +
    + if (bq20z75_device->pdata)
    + retries = max(bq20z75_device->pdata->i2c_retry_count + 1, 1);
    +
    + while (retries > 0) {
    + ret = i2c_smbus_read_word_data(client, address);
    + if (ret >= 0)
    + break;
    + retries--;
    + }

    - ret = i2c_smbus_read_word_data(client, address);
    if (ret < 0) {
    - dev_err(&client->dev,
    + dev_warn(&client->dev,
    "%s: i2c read at address 0x%x failed\n",
    __func__, address);
    return ret;
    }
    +
    return le16_to_cpu(ret);
    }

    static int bq20z75_write_word_data(struct i2c_client *client, u8 address,
    u16 value)
    {
    - s32 ret;
    + struct bq20z75_info *bq20z75_device = i2c_get_clientdata(client);
    + s32 ret = 0;
    + int retries = 1;
    +
    + if (bq20z75_device->pdata)
    + retries = max(bq20z75_device->pdata->i2c_retry_count + 1, 1);
    +
    + while (retries > 0) {
    + ret = i2c_smbus_write_word_data(client, address,
    + le16_to_cpu(value));
    + if (ret >= 0)
    + break;
    + retries--;
    + }

    - ret = i2c_smbus_write_word_data(client, address, le16_to_cpu(value));
    if (ret < 0) {
    - dev_err(&client->dev,
    + dev_warn(&client->dev,
    "%s: i2c write to address 0x%x failed\n",
    __func__, address);
    return ret;
    }
    +
    return 0;
    }

    diff --git a/include/linux/power/bq20z75.h b/include/linux/power/bq20z75.h
    index 0e1b8a2..b0843b6 100644
    --- a/include/linux/power/bq20z75.h
    +++ b/include/linux/power/bq20z75.h
    @@ -28,10 +28,12 @@
    * struct bq20z75_platform_data - platform data for bq20z75 devices
    * @battery_detect: GPIO which is used to detect battery presence
    * @battery_detect_present: gpio state when battery is present (0 / 1)
    + * @i2c_retry_count: # of times to retry on i2c IO failure
    */
    struct bq20z75_platform_data {
    int battery_detect;
    int battery_detect_present;
    + int i2c_retry_count;
    };

    #endif
    --
    1.7.0.4


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