Eugen, On 02/09/2019 14:15:14+0000, Eugen.Hristev@xxxxxxxxxxxxx wrote: > On 02.09.2019 13:49, Peter Rosin wrote: > > > On 2019-09-02 12:12, Eugen.Hristev@xxxxxxxxxxxxx wrote: > >> From: Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx> > >> > >> Some i2c controllers have a built-in digital or analog filter. > >> This is specifically required depending on the hardware PCB/board. > >> Some controllers also allow specifying the maximum width of the > >> spikes that can be filtered. The width length can be specified in nanoseconds. > >> > >> Signed-off-by: Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx> > >> --- > >> Documentation/devicetree/bindings/i2c/i2c.txt | 11 +++++++++++ > >> 1 file changed, 11 insertions(+) > >> > >> diff --git a/Documentation/devicetree/bindings/i2c/i2c.txt b/Documentation/devicetree/bindings/i2c/i2c.txt > >> index 44efafd..8dbff67 100644 > >> --- a/Documentation/devicetree/bindings/i2c/i2c.txt > >> +++ b/Documentation/devicetree/bindings/i2c/i2c.txt > >> @@ -55,6 +55,17 @@ wants to support one of the below features, it should adapt the bindings below. > >> Number of nanoseconds the SDA signal takes to fall; t(f) in the I2C > >> specification. > >> > >> +- i2c-analog-filter > >> + Enable analog filter for i2c lines. > >> + > >> +- i2c-digital-filter > >> + Enable digital filter for i2c lines. > >> + > >> +- i2c-filter-width-ns > >> + Width of spikes which can be filtered by either digital or analog > >> + filters (i2c-analog-filtr or i2c-digital-filtr). This width is specified > > > > filtr -> filter (two instances) > > > > What if you want/need to have different bandwidth for the digital and analog > > filters? After all, this is a generic binding... > > For our needs, this is enough: the purpose of the filters is to avoid > noise on the lines, the noise is as big as it is for the digital and for > the analog filters, since we use an absolute measurement for them. So I > do not know how useful it would be to make a difference. > You are adding generic properties so they have to be generic and not tied to your particular use case. -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
