On Sat, Nov 17, 2018 at 6:35 PM tom burkart <tom@xxxxxxxxxx> wrote: > > Quoting Rob Herring <robh@xxxxxxxxxx>: > > > On Sat, Nov 17, 2018 at 4:35 AM tom burkart <tom@xxxxxxxxxx> wrote: > >> > >> Quoting Rob Herring <robh@xxxxxxxxxx>: > >> > >> > On Wed, Nov 14, 2018 at 11:54:29PM +1100, Tom Burkart wrote: > >> >> This patch changes the devicetree bindings for the pps-gpio driver > >> >> from the integer based ABI to the descriptor based ABI. > >> > ? That has nothing to do with DT. > >> > >> I believe it does, as the change in ABI forces a rename in the DT > >> naming convention. > >> This is due to the descriptor based ABI appending "-gpio" or "-gpios" (see > >> Documentation/gpio/base.txt.) > >> Admittedly, I may have called it by the wrong name due to ignorance, > >> my apologies. > > > > If what you say is correct, then you can't change this driver. You'll > > break compatibility with any existing DT. > > > > Changing the binding reasoning should purely be that this is the > > preferred form. Bindings must be independent from changing kernel > > APIs. > > See comments from Philip Zabel. I misread the documentation and this > has now been corrected in v8 of the patch. I hope that eliminates all > comments made above. > > >> >> It also adds > >> >> documentation for the device tree capture-clear option. The legacy > >> >> device tree entry for the GPIO pin is supported. > >> >> > >> >> Signed-off-by: Tom Burkart <tom@xxxxxxxxxx> > >> >> --- > >> >> Documentation/devicetree/bindings/pps/pps-gpio.txt | 8 ++++++-- > >> >> 1 file changed, 6 insertions(+), 2 deletions(-) > >> >> > >> >> diff --git a/Documentation/devicetree/bindings/pps/pps-gpio.txt > >> >> b/Documentation/devicetree/bindings/pps/pps-gpio.txt > >> >> index 3683874832ae..6c9fc0998d94 100644 > >> >> --- a/Documentation/devicetree/bindings/pps/pps-gpio.txt > >> >> +++ b/Documentation/devicetree/bindings/pps/pps-gpio.txt > >> >> @@ -5,19 +5,23 @@ a GPIO pin. > >> >> > >> >> Required properties: > >> >> - compatible: should be "pps-gpio" > >> >> -- gpios: one PPS GPIO in the format described by ../gpio/gpio.txt > >> >> +- pps-gpios: one PPS GPIO in the format described by ../gpio/gpio.txt > >> >> +Alternatively (DEPRECATED), instead of pps-gpios above, it may have: > >> >> +- gpios: one PPS GPIO as above > >> >> > >> >> 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 > >> > > >> > Is this a h/w thing? or driver configuration? > >> > >> Driver configuration. Most of the code was present in the driver, yet > >> it was not documented, or usable due to a two line (code) omission > >> (the value was not being fetched from DT). > > > > So what determines how you want to configure this? If the user will > > want to change it, then it should be a sysfs attr and exposed to > > userspace. If it depends on h/w config for a board then it can be in > > DT. > > Sorry, I misled you somewhat. If the PPS pulse active transition from > the hardware is on the falling edge, this flag is required to get the > OS to use that as the active transition. This would not change at the > user's whim but rather it is dependent on connected hardware. This description sounds more like 'assert-falling-edge' than 'capture-clear'. I'm still not clear on what 'capture-clear' is. Rob
