Re: [PATCH v7 03/15] i2c: octeon: Remove I2C_FUNC_SMBUS_QUICK support

Wolfram Sang
2016-04-25T22:16:28Z

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On Mon, Apr 25, 2016 at 04:33:32PM +0200, Jan Glauber wrote:
> SMBUS QUICK never worked for the read case, because EINVAL was returned
> for a zero length message. The hardware does not support SMBUS QUICK
> messages so disable the support and remove the zero length check.
>
> Signed-off-by: Jan Glauber <jglauber@cavium.com>

I see better now and I think we need to drop this patch. It looks like
the driver supports only SMBUS_QUICK_WRITE which can be used for
scanning devices. The driver probably works with 'i2cdetect -q'. This
will regress if I apply the patch.

It seems it can't do SMBUS_QUICK_READ thus the extra check in the code.

I2C_FUNC_SMBUS_QUICK should have been split up in READ and WRITE to
support this scenario.

Are my assumptions correct?

> ---
> drivers/i2c/busses/i2c-octeon.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-octeon.c b/drivers/i2c/busses/i2c-octeon.c
> index 0f536a1..ad563cf 100644
> --- a/drivers/i2c/busses/i2c-octeon.c
> +++ b/drivers/i2c/busses/i2c-octeon.c
> @@ -459,9 +459,6 @@ static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
> int i, result, length = *rlength;
> bool final_read = false;
>
> - if (length < 1)
> - return -EINVAL;
> -
> octeon_i2c_data_write(i2c, (target << 1) | 1);
> octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
>
> @@ -597,7 +594,7 @@ static struct i2c_bus_recovery_info octeon_i2c_recovery_info = {
>
> static u32 octeon_i2c_functionality(struct i2c_adapter *adap)
> {
> - return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
> + return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK) |
> I2C_FUNC_SMBUS_READ_BLOCK_DATA | I2C_SMBUS_BLOCK_PROC_CALL;
> }
>
> --
> 1.9.1
>

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