On Fri, Oct 30, 2020 at 12:42 PM Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> wrote: > > Hi Rob, > > On Mon, Oct 26, 2020 at 09:17:14AM -0500, Rob Herring wrote: > > On Thu, Oct 22, 2020 at 02:56:17PM +0000, Hugues FRUCHET wrote: > > > Hi Sakari, > > > > > > + Jacopo for his work on ov772x binding related to BT656 > > > > > > On 10/21/20 11:40 PM, Sakari Ailus wrote: > > > > Hi Hugues, > > > > > > > > On Wed, Oct 21, 2020 at 02:24:08PM +0000, Hugues FRUCHET wrote: > > > >> Hi Sakari, > > > >> > > > >> On 10/21/20 3:00 PM, Sakari Ailus wrote: > > > >>> Hi Hugues, > > > >>> > > > >>> On Tue, Oct 20, 2020 at 12:14:49PM +0200, Hugues Fruchet wrote: > > > >>>> Add support of BT656 parallel bus mode in DCMI. > > > >>>> This mode is enabled when hsync-active & vsync-active > > > >>>> fields are not specified. > > > >>>> > > > >>>> Signed-off-by: Hugues Fruchet <hugues.fruchet@xxxxxx> > > > >>>> --- > > > >>>> .../devicetree/bindings/media/st,stm32-dcmi.yaml | 30 ++++++++++++++++++++++ > > > >>>> 1 file changed, 30 insertions(+) > > > >>>> > > > >>>> diff --git a/Documentation/devicetree/bindings/media/st,stm32-dcmi.yaml b/Documentation/devicetree/bindings/media/st,stm32-dcmi.yaml > > > >>>> index 3fe778c..1ee521a 100644 > > > >>>> --- a/Documentation/devicetree/bindings/media/st,stm32-dcmi.yaml > > > >>>> +++ b/Documentation/devicetree/bindings/media/st,stm32-dcmi.yaml > > > >>>> @@ -44,6 +44,36 @@ properties: > > > >>>> bindings defined in > > > >>>> Documentation/devicetree/bindings/media/video-interfaces.txt. > > > >>>> > > > >>>> + properties: > > > >>>> + endpoint: > > > >>>> + type: object > > > >>>> + > > > >>>> + properties: > > > >>>> + bus-width: true > > > >>>> + > > > >>>> + hsync-active: > > > >>>> + description: > > > >>>> + If both HSYNC and VSYNC polarities are not specified, BT656 > > > >>>> + embedded synchronization is selected. > > > >>>> + default: 0 > > > >>>> + > > > >>>> + vsync-active: > > > >>>> + description: > > > >>>> + If both HSYNC and VSYNC polarities are not specified, BT656 > > > >>>> + embedded synchronization is selected. > > > >>>> + default: 0 > > > >>> > > > >>> Should I understand this as if the polarities were not specified, BT.656 > > > >>> will be used? > > > >> > > > >> Yes, this is what is documented in video-interfaces.txt: > > > >> " > > > >> Note, that if HSYNC and VSYNC polarities are not specified, embedded > > > >> synchronization may be required, where supported. > > > >> " > > > >> and > > > >> " > > > >> /* If hsync-active/vsync-active are missing, > > > >> embedded BT.656 sync is used */ > > > >> hsync-active = <0>; /* Active low */ > > > >> vsync-active = <0>; /* Active low */ > > > >> " > > > >> and I found also this in > > > >> Documentation/devicetree/bindings/media/renesas,vin.yaml > > > >> " > > > >> hsync-active: > > > >> description: > > > >> If both HSYNC and VSYNC polarities are not specified, > > > >> embedded > > > >> synchronization is selected. > > > >> default: 1 > > > >> > > > >> vsync-active: > > > >> description: > > > >> If both HSYNC and VSYNC polarities are not specified, > > > >> embedded > > > >> synchronization is selected. > > > >> default: 1 > > > > > > > > Having the defaults leads to somewhat weird behaviour: specifying the > > > > default value on either property changes the bus type. > > > > > > > >> " > > > >> > > > >> In the other hand I've found few occurences of "bus-type" > > > >> (marvell,mmp2-ccic.yaml), it is why I asked you if "bus-type" is the new > > > >> way to go versus previous way to signal BT656 (without hsync/vsync) ? > > > >> As explained previously, I prefer this last way for backward compatibility. > > > > > > > > If you have a default for bus-type (BT.601), this won't be a problem. > > > > > > > > The old DT bindings were somewhat, well, opportunistic. The v4l2-of > > > > framework-let did its best and sometimes it worked. The behaviour is still > > > > supported but not encouraged in new bindings. > > > > > > > > > > OK, so let's go for the new way. > > > I've found an interesting patch from Jacopo that is of great help: > > > https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20200910162055.614089-4-jacopo+renesas@xxxxxxxxxx/ > > I wonder if Jacopo tested it. The idea seems interesting nonetheless. > > > > > > > Here is a draft proposal before I push a new version, please comment: > > > > > > properties: > > > bus-type: > > > enum: [5, 6] > > > default: 5 > > > > > > bus-width: > > > enum: [8, 10, 12, 14] > > > default: 8 > > > > > > hsync-active: > > > enum: [0, 1] > > > > For common properties, you can assume there's a common schema. As 0 and > > 1 are the only possible values, you don't need to define them here > > unless only a subset is valid for this device. > > > > > default: 0 > > > > > > vsync-active: > > > enum: [0, 1] > > > default: 0 > > > > > > pclk-sample: > > > enum: [0, 1] > > > default: 0 > > > > > > remote-endpoint: true > > > > > > allOf: > > > - if: > > > properties: > > > bus-type: > > > const: 6 > > > > To fix the error, you need: > > > > required: > > - bus-type > > > > The problem is the above schema is also true if the property > > is not present. > > Hmm. The idea was that we could keep this consistent with old bindings that > only documented parallel mode, and thus didn't need bus-type. This is > actually quite common --- adding support for something that wasn't known or > cared for during the original review. TBC, the 'required' here is required for the 'if' in the if/then schema to work as you want. It's not making 'bus-type' a required property. Rob
