Messages in this thread | | | Date | Tue, 27 Nov 2018 15:06:29 +1100 | From | tom burkart <> | Subject | Re: [PATCH v9 3/4] dt-bindings: pps: pps-gpio PPS ECHO implementation |
| |
Hi Rob,
Quoting Rob Herring <robh@kernel.org>:
> On Thu, Nov 22, 2018 at 3:49 AM Tom Burkart <tom@aussec.com> wrote: >> >> This patch implements the device tree changes required for the pps >> echo functionality for pps-gpio, that sysfs claims is available >> already. >> >> This patch was originally written by Lukas Senger as part of a masters >> thesis project and modified for inclusion into the linux kernel by Tom >> Burkart. >> >> Signed-off-by: Lukas Senger <lukas@fridolin.com> >> Signed-off-by: Tom Burkart <tom@aussec.com> >> --- >> Documentation/devicetree/bindings/pps/pps-gpio.txt | 9 +++++++++ >> 1 file changed, 9 insertions(+) >> >> diff --git a/Documentation/devicetree/bindings/pps/pps-gpio.txt >> b/Documentation/devicetree/bindings/pps/pps-gpio.txt >> index 1155d49c2699..e09f6f2405c5 100644 >> --- a/Documentation/devicetree/bindings/pps/pps-gpio.txt >> +++ b/Documentation/devicetree/bindings/pps/pps-gpio.txt >> @@ -7,10 +7,15 @@ Required properties: >> - compatible: should be "pps-gpio" >> - gpios: one PPS GPIO in the format described by ../gpio/gpio.txt >> >> +Additional required properties for the PPS ECHO functionality: >> +- echo-gpios: one PPS ECHO GPIO in the format described by ../gpio/gpio.txt >> +- echo-active-ms: duration in ms of the active portion of the echo pulse >> + >> Optional properties: >> - assert-falling-edge: when present, assert is indicated by a falling edge >> (instead of by a rising edge) >> - capture-clear: when present, also capture the PPS clear event >> +- invert-pps-echo: when present, invert the PPS ECHO pulse > > Why do you need this? Can't you just make the echo gpio GPIO_ACTIVE_LOW? > > BTW, using the flag probably should have been done for > 'assert-falling-edge' as well.
The hardware I use expects a positive-going echo pulse, however, it was really easy to give users the option to have it inverted in case they use different hardware that expects a negative-going edge.
I may well be needing this option myself if I find that the GPS I am using produces better results for negative-going edges than positive-going edges.
Tom
| |