On Fri, Jul 10, 2020 at 1:33 AM Benjamin GAIGNARD <benjamin.gaignard@xxxxxx> wrote: > > > > On 7/9/20 10:37 PM, Rob Herring wrote: > > On Wed, Jul 01, 2020 at 03:01:27PM +0200, Benjamin Gaignard wrote: > >> Document st,stm32-dcmi-min-frequency property which is used to > >> request CPUs minimum frequency when streaming frames. > >> > >> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxx> > >> --- > >> Documentation/devicetree/bindings/media/st,stm32-dcmi.yaml | 8 ++++++++ > >> 1 file changed, 8 insertions(+) > >> > >> diff --git a/Documentation/devicetree/bindings/media/st,stm32-dcmi.yaml b/Documentation/devicetree/bindings/media/st,stm32-dcmi.yaml > >> index 3fe778cb5cc3..05ca85a2411a 100644 > >> --- a/Documentation/devicetree/bindings/media/st,stm32-dcmi.yaml > >> +++ b/Documentation/devicetree/bindings/media/st,stm32-dcmi.yaml > >> @@ -44,6 +44,13 @@ properties: > >> bindings defined in > >> Documentation/devicetree/bindings/media/video-interfaces.txt. > >> > >> + st,stm32-dcmi-min-frequency: > >> + description: DCMI minimum CPUs frequency requirement (in KHz). > >> + allOf: > >> + - $ref: /schemas/types.yaml#/definitions/uint32 > >> + - minimum: 0 > >> + - default: 0 > > I think this is questionable to be in DT and if it is, it's something > > that's hardly specific to ST or this block. IIRC, we already have a way > > to specify minimum OPPs. > This binding is only needed on some STM32 SoC when DVFS is activated > with low frequency setting in opp. The value also depends of the targeted > video format and framerate. As those 2 things are not in the DT, then neither should this value be. > It is not an opp because it doesn't define a voltage-current-frequency > combination > but only set a minimum target for the CPUs frequency to guaranty a good > reaction > time when handling IRQs for the sensor. OPPs can be frequency only. This is pretty clearly defining the CPU must Operate at a certain minimum Performance Point. Rob
