Re: [PATCH 5/7] iio: mlx90614: Allow tuning EEPROM configuration

[Wolfram Sang <wsa@the-dreams.de>]

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On Mon, Mar 09, 2015 at 05:02:31PM +0000, Jonathan Cameron wrote:
> On 09/03/15 16:45, Wolfram Sang wrote:
> > On Mon, Mar 09, 2015 at 03:41:30PM +0000, Jonathan Cameron wrote:
> >> On 09/03/15 15:35, Jonathan Cameron wrote:
> >>> On 25/02/15 15:55, Vianney le Clément de Saint-Marcq wrote:
> >>>> Add device attributes for getting/setting emissivity, IIR, and FIR
> >>>> coefficients, and getting the gain (which should not be modified in
> >>>> order to keep factory calibration).
> >>>>
> >>>> The attributes provide raw values whose meaning is described in the
> >>>> datasheet [1].
> >>>>
> >>>> Writing to EEPROM requires an explicit erase by writing zero.  In
> >>>> addition, it takes 20ms for the erase/write to complete.  During this
> >>>> time no EEPROM register should be accessed.  Therefore, two msleep()s
> >>>> are added to the write function and a mutex protects against concurrent
> >>>> access.
> >>>>
> >>>> Since it is not expected to be updated frequently, the configuration
> >>>> register is read before modifying it rather than caching it.
> >>>>
> >>>> [1] http://melexis.com/Assets/IR-sensor-thermometer-MLX90614-Datasheet-5152.aspx
> >>>>
> >>>> Signed-off-by: Vianney le Clément de Saint-Marcq <vianney.leclement@essensium.com>
> >>>> Cc: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
> >>> Wolfram, bit of odd i2c usage inline I'd like you to take quick look at.
> > 
> > What do you mean? The direct calls to i2c_smbus_xfer? Was there any
> > reason given to use it directly?
> Apparently the returned PEC is present but wrong.  However it requires
> a correct PEC to be transmitted to it.  Genious

Ouch. Well, in such a case I think it is okay to call i2c_smbus_transfer
directly, especially since it is described well in the comment. lm90
does this, too. But there, it is the writes that are broken. I don't
feel to add quirk flags for all possible permutations of this problem.


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