On Fri, Sep 3, 2021 at 12:29 PM Mikko Perttunen cyndis@kapsi.fi wrote:
On 9/3/21 7:34 PM, Rob Herring wrote:
On Fri, Sep 03, 2021 at 11:31:53AM +0300, Mikko Perttunen wrote:
Add YAML device tree bindings for NVDEC, now in a more appropriate place compared to the old textual Host1x bindings.
Signed-off-by: Mikko Perttunen mperttunen@nvidia.com
v4:
- Fix incorrect compatibility string in 'if' condition
v3:
- Drop host1x bindings
- Change read2 to read-1 in interconnect names
v2:
- Fix issues pointed out in v1
- Add T194 nvidia,instance property
.../gpu/host1x/nvidia,tegra210-nvdec.yaml | 109 ++++++++++++++++++ MAINTAINERS | 1 + 2 files changed, 110 insertions(+) create mode 100644 Documentation/devicetree/bindings/gpu/host1x/nvidia,tegra210-nvdec.yaml
diff --git a/Documentation/devicetree/bindings/gpu/host1x/nvidia,tegra210-nvdec.yaml b/Documentation/devicetree/bindings/gpu/host1x/nvidia,tegra210-nvdec.yaml new file mode 100644 index 000000000000..33d01c7dc759 --- /dev/null +++ b/Documentation/devicetree/bindings/gpu/host1x/nvidia,tegra210-nvdec.yaml @@ -0,0 +1,109 @@ +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) +%YAML 1.2 +--- +$id: "http://devicetree.org/schemas/gpu/host1x/nvidia,tegra210-nvdec.yaml#" +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+title: Device tree binding for NVIDIA Tegra NVDEC
+description: |
- NVDEC is the hardware video decoder present on NVIDIA Tegra210
- and newer chips. It is located on the Host1x bus and typically
- programmed through Host1x channels.
+maintainers:
- Thierry Reding treding@gmail.com
- Mikko Perttunen mperttunen@nvidia.com
+properties:
- $nodename:
- pattern: "^nvdec@[0-9a-f]*$"
- compatible:
- enum:
- nvidia,tegra210-nvdec- nvidia,tegra186-nvdec- nvidia,tegra194-nvdec- reg:
- maxItems: 1
- clocks:
- maxItems: 1
- clock-names:
- items:
- const: nvdec- resets:
- maxItems: 1
- reset-names:
- items:
- const: nvdec- power-domains:
- maxItems: 1
- iommus:
- maxItems: 1
- interconnects:
- items:
- description: DMA read memory client- description: DMA read 2 memory client- description: DMA write memory client- interconnect-names:
- items:
- const: dma-mem- const: read-1- const: write+required:
- compatible
- reg
- clocks
- clock-names
- resets
- reset-names
- power-domains
+if:
- properties:
- compatible:
contains:const: nvidia,tegra194-nvdec+then:
- properties:
- nvidia,instance:
items:- description: 0 for NVDEC0, or 1 for NVDEC1I still don't understand what this is needed for. What is the difference between the instances? There must be some reason you care. We should describe that difference, not some made up index.
I'm not suggesting using the base address either. That's fragile too.
This device is on the Host1x bus. On that bus, each device has an identifier baked into hardware called 'class' that is used when accessing devices through some mechanisms (host1x channels). As such, when probing the device we need to specify the class of the device to the host1x driver so it knows how to talk to it. Those class numbers are fixed so we have hardcoded them in the driver, but now that we have two NVDECs, we need to distinguish between them so that we can specify the correct class for each instance to the host1x driver.
Then why don't you have a property like 'nvidia,host1x-class' containing the class number?
+additionalProperties: true
'true' here is not allowed unless the schema is not complete and intended to be included in a complete schema or unconditionally applied (i.e. 'select: true'). This case is neither. As pointed out previously, 'unevaluatedProperties' is what you'd want here.
However, I looked into supporting defining properties in if/then/else schemas as you have done and I don't think we will support that soon. It's problematic because we can't validate the schema under the if/then completely. The reason is properties under if/then schemas don't have to be complete as we expect a top level definition that is complete (e.g. vendor properties must have 'description'). To solve this, we'd have to only apply meta-schema checks if the property doesn't appear at the top level. That's more complicated than I care to implement ATM.
I see two paths here: either keep 'additionalProperties: true' or remove it and have this binding trigger validation failures. Which one do you suggest or is there some third option?
Define the property at the top level, then restrict it in the if/then schema:
if: properties: compatible: not: contains: const: nvidia,tegra194-nvdec then: properties: nvidia,instance: false
(Or 'not: {required: [ nvidia,instance ]}' would work here, too)
With that, 'additionalProperties: false' will work.
Rob