linux-kernel - Re: [PATCH 4/8 v3] i2c: i801: check and return errors during byte-by-byte transfers

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Date:	Wed, 27 Jun 2012 18:51:36 +0200
From:	Jean Delvare <khali@...ux-fr.org>
To:	Daniel Kurtz <djkurtz@...omium.org>
Cc:	Ben Dooks <ben-linux@...ff.org>,
	Wolfram Sang <w.sang@...gutronix.de>,
	Seth Heasley <seth.heasley@...el.com>,
	Olof Johansson <olof@...om.net>,
	Benson Leung <bleung@...omium.org>, linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/8 v3] i2c: i801: check and return errors during
 byte-by-byte transfers

On Wed, 27 Jun 2012 21:54:11 +0800, Daniel Kurtz wrote:
> If an error is detected in the polling loop, abort the transaction and
> return an error code.
> 
>  * DEV_ERR is set if the device does not respond with an acknowledge, and
> the SMBus controller times out (minimum 25ms).
>  * BUS_ERR is set if a bus arbitration collision is detected.  In other
> words, when the SMBus controller tries to generate a START condition, but
> detects that the SMBDATA is being held low, usually by another SMBus/I2C
> master.
>  * FAILED is only set if a the transaction is set by software (using the
> SMBHSTCNT KILL bit).

Not quite sure what you mean with "set by software". Other than this,
patch looks good, applied, thanks.

> 
> Signed-off-by: Daniel Kurtz <djkurtz@...omium.org>
> ---
>  drivers/i2c/busses/i2c-i801.c |   10 ++++++----
>  1 files changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
> index 6a53338..ba56b74 100644
> --- a/drivers/i2c/busses/i2c-i801.c
> +++ b/drivers/i2c/busses/i2c-i801.c
> @@ -131,9 +131,11 @@
>  #define SMBHSTSTS_INTR		0x02
>  #define SMBHSTSTS_HOST_BUSY	0x01
>  
> -#define STATUS_FLAGS		(SMBHSTSTS_BYTE_DONE | SMBHSTSTS_FAILED | \
> -				 SMBHSTSTS_BUS_ERR | SMBHSTSTS_DEV_ERR | \
> -				 SMBHSTSTS_INTR)
> +#define STATUS_ERROR_FLAGS	(SMBHSTSTS_FAILED | SMBHSTSTS_BUS_ERR | \
> +				 SMBHSTSTS_DEV_ERR)
> +
> +#define STATUS_FLAGS		(SMBHSTSTS_BYTE_DONE | SMBHSTSTS_INTR | \
> +				 STATUS_ERROR_FLAGS)
>  
>  /* Older devices have their ID defined in <linux/pci_ids.h> */
>  #define PCI_DEVICE_ID_INTEL_COUGARPOINT_SMBUS	0x1c22
> @@ -385,7 +387,7 @@ static int i801_block_transaction_byte_by_byte(struct i801_priv *priv,
>  		do {
>  			usleep_range(250, 500);
>  			status = inb_p(SMBHSTSTS(priv));
> -		} while ((!(status & SMBHSTSTS_BYTE_DONE))
> +		} while (!(status & (SMBHSTSTS_BYTE_DONE | STATUS_ERROR_FLAGS))
>  			 && (timeout++ < MAX_RETRIES));
>  
>  		result = i801_check_post(priv, status, timeout > MAX_RETRIES);


-- 
Jean Delvare
--
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