lkml.org 
[lkml]   [2022]   [Oct]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH v2 4/5] iio: accel: Support Kionix/ROHM KX022A accelerometer
On Thu, 6 Oct 2022 21:32:11 +0300
Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:

> On Thu, Oct 06, 2022 at 05:38:14PM +0300, Matti Vaittinen wrote:
> > KX022A is a 3-axis accelerometer from ROHM/Kionix. The senosr features
> > include variable ODRs, I2C and SPI control, FIFO/LIFO with watermark IRQ,
> > tap/motion detection, wake-up & back-to-sleep events, four acceleration
> > ranges (2, 4, 8 and 16g) and probably some other cool features.
> >
> > Add support for the basic accelerometer features such as getting the
> > acceleration data via IIO. (raw reads, triggered buffer [data-ready] or
> > using the WMI IRQ).
> >
> > Important things to be added include the double-tap, motion
> > detection and wake-up as well as the runtime power management.
> >
> > NOTE: Filling-up the hardware FIFO should be avoided. During my testing
> > I noticed that filling up the hardware FIFO might mess-up the sample
> > count. My sensor ended up in a state where the amount of data in FIFO was
> > reported to be 0xff bytes, which equals to 42,5 samples. Specification
> > says the FIFO can hold a maximum of 41 samples in HiRes mode. Also, at
> > least once the FIFO was stuck in a state where reading data from
> > hardware FIFO did not decrease the amount of data reported to be in the
> > FIFO - eg. FIFO was "stuck". The code has now an error count and 10
> > reads with invalid FIFO data count will cause the fifo contents to be
> > dropped.
>

> ...
...



> ...
>
> > +module_param(g_kx022a_use_buffer, bool, 0);
> > +MODULE_PARM_DESC(g_kx022a_use_buffer,
> > + "Buffer samples. Use at own risk. Fifo must not overflow");
>
> Why?! We usually do not allow module parameters in the new code.
>

Badly broken hardware - was my suggestion. Alternatives if there are usecases
that need to use the fifo, but it can wedge hard in a fashion that is impossible
to prevent from the driver? My gut feeling is still drop the support entirely
with a strong comment in the code that the hardware is broken in a fashion we don't
know how to work around.

Jonathan


\
 
 \ /
  Last update: 2022-10-09 14:34    [W:0.230 / U:0.764 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site