On 6/25/2023 6:46 PM, Krzysztof Kozlowski wrote:
On 25/06/2023 16:21, Eliav Farber wrote:
Add a new optional "capture-clear" boolean property.
When present, PPS clear events shall also be reported.
Signed-off-by: Eliav Farber <farbere@xxxxxxxxxx>
---
Documentation/devicetree/bindings/pps/pps-gpio.txt | 4 ++++
Please convert the bindings to DT schema first.
I will convert to DT schema first, if I indeed end up modifying this file.
1 file changed, 4 insertions(+)
diff --git a/Documentation/devicetree/bindings/pps/pps-gpio.txt
b/Documentation/devicetree/bindings/pps/pps-gpio.txt
index 9012a2a02e14..8d588e38c44e 100644
--- a/Documentation/devicetree/bindings/pps/pps-gpio.txt
+++ b/Documentation/devicetree/bindings/pps/pps-gpio.txt
@@ -14,6 +14,10 @@ Additional required properties for the PPS ECHO
functionality:
Optional properties:
- assert-falling-edge: when present, assert is indicated by a
falling edge
(instead of by a rising edge)
+- capture-clear: when present, report also PPS clear events, which
is the
+ opposite of the assert edge (if assert is
rising-edge then
+ clear is falling-edge and if assert is falling-edge
then
+ clear is rising-edge).
Why this is board-dependant? Falling edge is happening anyway, so it is
in the hardware all the time. DT describes the hardware, not Linux
driver behavior.
Falling edge of the pulse is happening all the time, but the falling
edge event is currently never reported by the pps-gpio driver.
It is because there is no place in the pps-gpio driver that sets
info->capture_clear, so
pps_event(info->pps, &ts, PPS_CAPTURECLEAR, data);
will never be called.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pps/clients/pps-gpio.c?h=v6.4#n59
There was an option in the past to set info->capture_clear, but that
option was removed in commit ee89646619ba ("pps: clients: gpio: Get rid
of legacy platform data").
This node in the DT isn't a pure HW device, but rather a SW driver.
The patch I shared allows to set capture-clear from device-tree same as
setting of assert-falling-edge is done.
Do you suggest I enable capture_clear in a different way?
Perhaps module-param?
What's more, your property name sounds a lot like a driver property, so
even if this is suitable for DT, you would need to name it properly to
match hardware feature/characteristic.
I chose capture-clear as a name since it is aligned with the driver's
terminology. It sets the capture_clear parameter, just like
assert-falling-edge in DT sets assert_falling_edge parameter.
---
Regards, Eliav
