Re: Linux Kernel: Bug in the bmc150 driver

Re: Linux Kernel: Bug in the bmc150 driver

[Jonathan Cameron]

On Mon, 26 Aug 2019 06:58:26 +0200
Pascal Bouwmann <bouwmann@tau-tec.de> wrote:

> Dear Mr. Cameron,
> 
> in the bmc150 driver I probably found a mistake:
> In the datasheets of the supported devices it is written that the 
> central temperature is 23°C (see links below).

Hi. This is curious.  
> 
> BMC150: 
> https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMC150-DS000.pdf, 
> page 27

Look at page 72 where the register is defined and there the 0 value is specified as 24.

I haven't checked the others but at a quick glance at this one case it would seem the
data sheets are internally inconsistent.

I'm inclined to go with the version provided with the register definition rather than
the descriptive text, but obviously the best option would be to get a clarification
on this from Bosch.

Thanks,

Jonathan

> BMI055: 
> https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMI055-DS000.pdf, 
> page 23
> BMA255: 
> https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMA255-DS004.pdf, 
> page 19
> BMA250E: 
> https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMA250E-DS004.pdf, 
> page 19
> BMA222E: 
> https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMA222E-DS004.pdf, 
> page 19
> BMA280: 
> https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMA280-DS000.pdf, 
> page 19
> 
> In the driver drivers/iio/accel/bmc150-accel-core.c the constant 
> BMC150_ACCEL_TEMP_CENTER_VAL should therefore be 23 instead of 24.
> This constant is defined in line 
> 120:https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/drivers/iio/accel/bmc150-accel-core.c?h=v5.3-rc6
>