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Date:	Sat, 9 Feb 2013 18:25:16 +0100
From:	"Henrik Rydberg" <rydberg@...omail.se>
To:	Daniel Kurtz <djkurtz@...omium.org>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Benson Leung <bleung@...omium.org>,
	Yufeng Shen <miletus@...omium.org>,
	Nick Dyer <nick.dyer@...ev.co.uk>,
	Joonyoung Shim <jy0922.shim@...sung.com>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	olofj@...omium.org
Subject: Re: [PATCH 01/10] Input: atmel_mxt_ts - refactor i2c error handling

Hi Daniel,

> A recent patch refactored i2c error handling in the register read/write
> path.  This adds similar handling to the other i2c paths used in fw_update
> and bootloader state detection.
> 
> The generic i2c layer can return values indicating a partial transaction.
> From the atmel_mxt driver's perspective, this is an IO error, so we use
> some helper functions to convert these partial transfers to -EIO in a
> uniform way.  Other error codes might still be useful, though, so we pass
> them up unmodified.
> 
> Signed-off-by: Daniel Kurtz <djkurtz@...omium.org>
> ---
>  drivers/input/touchscreen/atmel_mxt_ts.c | 92 +++++++++++++++++++-------------
>  1 file changed, 54 insertions(+), 38 deletions(-)

Nice cleanup, but some comments below.

> 
> diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
> index d04f810..a222bd8 100644
> --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> @@ -324,16 +324,62 @@ static void mxt_dump_message(struct device *dev,
>  		message->reportid, 7, message->message);
>  }
>  
> +static int mxt_i2c_recv(struct i2c_client *client, u8 *buf, size_t count)
> +{
> +	int ret;
> +
> +	ret = i2c_master_recv(client, buf, count);
> +	if (ret == count) {
> +		ret = 0;
> +	} else if (ret != count) {

Eh, implied logic. Also, no need for an else here, just return 0 above.

> +		ret = (ret < 0) ? ret : -EIO;
> +		dev_err(&client->dev, "i2c recv failed (%d)\n", ret);
> +	}
> +
> +	return ret;
> +}
> +
> +static int mxt_i2c_send(struct i2c_client *client, const u8 *buf, size_t count)
> +{
> +	int ret;
> +
> +	ret = i2c_master_send(client, buf, count);
> +	if (ret == count) {
> +		ret = 0;
> +	} else if (ret != count) {

Ditto...

> +		ret = (ret < 0) ? ret : -EIO;
> +		dev_err(&client->dev, "i2c send failed (%d)\n", ret);
> +	}
> +
> +	return ret;
> +}
> +
> +static int mxt_i2c_transfer(struct i2c_client *client, struct i2c_msg *msgs,
> +		size_t count)
> +{
> +	int ret;
> +
> +	ret = i2c_transfer(client->adapter, msgs, count);
> +	if (ret == count) {
> +		ret = 0;

return 0;

> +	} else {

skip

> +		ret = (ret < 0) ? ret : -EIO;
> +		dev_err(&client->dev, "i2c transfer failed (%d)\n", ret);
> +	}
> +
> +	return ret;
> +}
> +
>  static int mxt_check_bootloader(struct i2c_client *client,
>  				     unsigned int state)
>  {
>  	u8 val;
> +	int ret;
>  
>  recheck:
> -	if (i2c_master_recv(client, &val, 1) != 1) {
> -		dev_err(&client->dev, "%s: i2c recv failed\n", __func__);
> -		return -EIO;
> -	}
> +	ret = mxt_i2c_recv(client, &val, 1);
> +	if (ret)
> +		return ret;
>  
>  	switch (state) {
>  	case MXT_WAITING_BOOTLOAD_CMD:
> @@ -363,23 +409,13 @@ static int mxt_unlock_bootloader(struct i2c_client *client)
>  	buf[0] = MXT_UNLOCK_CMD_LSB;
>  	buf[1] = MXT_UNLOCK_CMD_MSB;
>  
> -	if (i2c_master_send(client, buf, 2) != 2) {
> -		dev_err(&client->dev, "%s: i2c send failed\n", __func__);
> -		return -EIO;
> -	}
> -
> -	return 0;
> +	return mxt_i2c_send(client, buf, 2);
>  }
>  
>  static int mxt_fw_write(struct i2c_client *client,
>  			     const u8 *data, unsigned int frame_size)
>  {
> -	if (i2c_master_send(client, data, frame_size) != frame_size) {
> -		dev_err(&client->dev, "%s: i2c send failed\n", __func__);
> -		return -EIO;
> -	}
> -
> -	return 0;
> +	return mxt_i2c_send(client, data, frame_size);
>  }
>  
>  static int __mxt_read_reg(struct i2c_client *client,
> @@ -387,7 +423,6 @@ static int __mxt_read_reg(struct i2c_client *client,
>  {
>  	struct i2c_msg xfer[2];
>  	u8 buf[2];
> -	int ret;
>  
>  	buf[0] = reg & 0xff;
>  	buf[1] = (reg >> 8) & 0xff;
> @@ -404,17 +439,7 @@ static int __mxt_read_reg(struct i2c_client *client,
>  	xfer[1].len = len;
>  	xfer[1].buf = val;
>  
> -	ret = i2c_transfer(client->adapter, xfer, 2);
> -	if (ret == 2) {
> -		ret = 0;
> -	} else {
> -		if (ret >= 0)
> -			ret = -EIO;
> -		dev_err(&client->dev, "%s: i2c transfer failed (%d)\n",
> -			__func__, ret);
> -	}
> -
> -	return ret;
> +	return mxt_i2c_transfer(client, xfer, 2);
>  }
>  
>  static int mxt_read_reg(struct i2c_client *client, u16 reg, u8 *val)
> @@ -438,16 +463,7 @@ static int __mxt_write_reg(struct i2c_client *client, u16 reg, u16 len,
>  	buf[1] = (reg >> 8) & 0xff;
>  	memcpy(&buf[2], val, len);
>  
> -	ret = i2c_master_send(client, buf, count);
> -	if (ret == count) {
> -		ret = 0;
> -	} else {
> -		if (ret >= 0)
> -			ret = -EIO;
> -		dev_err(&client->dev, "%s: i2c send failed (%d)\n",
> -			__func__, ret);
> -	}
> -
> +	ret = mxt_i2c_send(client, buf, count);
>  	kfree(buf);
>  	return ret;
>  }
> -- 
> 1.8.1
> 

Thanks,
Henrik
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