Re: [PATCH v5 5/8] dt-bindings: media: add bindings for TI DS90UB960

Tomi Valkeinen
2022-12-13T14:26:08Z

On 11/12/2022 19:58, Laurent Pinchart wrote:
> Hi Tomi,
>
> Thank you for the patch.
>
> On Thu, Dec 08, 2022 at 12:40:03PM +0200, Tomi Valkeinen wrote:
>> Add DT bindings for TI DS90UB960 FPDLink-3 Deserializer.
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
>> ---
>> .../bindings/media/i2c/ti,ds90ub960.yaml | 358 ++++++++++++++++++
>> 1 file changed, 358 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml b/Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml
>> new file mode 100644
>> index 000000000000..d8b5e219d420
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml
>> @@ -0,0 +1,358 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/media/i2c/ti,ds90ub960.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Texas Instruments DS90UB9XX Family FPD-Link Deserializer Hubs
>> +
>> +maintainers:
>> + - Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
>> +
>> +description:
>> + The TI DS90UB9XX devices are FPD-Link video deserializers with I2C and GPIO
>> + forwarding.
>> +
>> +properties:
>> + compatible:
>> + enum:
>> + - ti,ds90ub960-q1
>> + - ti,ds90ub9702-q1
>> +
>> + reg:
>> + maxItems: 1
>> + description:
>> + i2c addresses for the deserializer and the serializers
>
> s/i2c/I2C/
>
> Same below.
>
> A bit more details would be nice, for instance the order in which
> addresses should be specified should be documented. The example below
> has one address only, so it's quite unclear. Or is this a left-over,
> from before the i2c-alias-pool ?

That's a left over, but not related to i2c-alias-pool but the i2c-alias
for the serializers. It already says above 'maxItems: 1', so now it only
contains the deserializer address. I'll drop the desc.

>> +
>> + clocks:
>> + maxItems: 1
>> + description:
>> + Reference clock connected to the REFCLK pin.
>> +
>> + clock-names:
>> + items:
>> + - const: refclk
>> +
>> + powerdown-gpios:
>> + maxItems: 1
>> + description:
>> + Specifier for the GPIO connected to the PDB pin.
>> +
>> + i2c-alias-pool:
>> + $ref: /schemas/types.yaml#/definitions/uint16-array
>> + description:
>> + i2c alias pool is a pool of i2c addresses on the main i2c bus that can be
>> + used to access the remote peripherals. The addresses must be available,
>> + not used by any other peripheral. Each remote peripheral is assigned an
>> + alias from the pool, and transactions to that address will be forwarded
>> + to the remote peripheral, with the address translated to the remote
>> + peripheral's real address.
>
> As this property is optional, should you describe what happens when it's
> not specified ?
>
> I would also indicate that the pool doesn't cover the serializers, only
> the devices behind them.

Yep, I'll clarify these.

>> +
>> + links:
>> + type: object
>> + additionalProperties: false
>> +
>> + properties:
>> + '#address-cells':
>> + const: 1
>> +
>> + '#size-cells':
>> + const: 0
>> +
>> + ti,manual-strobe:
>> + type: boolean
>> + description:
>> + Enable manual strobe position and EQ level
>> +
>> + patternProperties:
>> + '^link@[0-9a-f]+$':
>
> There can be up to 4 links only, right ? I would then use
>
> '^link@[0-3]$':

Yes, I'll change that.

>> + type: object
>> + additionalProperties: false
>> + properties:
>> + reg:
>> + description: The link number
>> + maxItems: 1
>> +
>> + i2c-alias:
>> + description:
>> + The i2c address used for the serializer. Transactions to this
>> + address on the i2c bus where the deserializer resides are
>> + forwarded to the serializer.
>> +
>> + ti,rx-mode:
>> + $ref: /schemas/types.yaml#/definitions/uint32
>> + enum:
>> + - 0 # RAW10
>> + - 1 # RAW12 HF
>> + - 2 # RAW12 LF
>> + - 3 # CSI2 SYNC
>> + - 4 # CSI2 NON-SYNC
>> + description: FPD-Link Input Mode
>
> Are there use cases for controlling this dynamically (in particular the
> sync/non-sync modes) ? Is there anything that could be queried at
> runtime from the serializers instead of being specified in DT ?

We need a link to the serializer before we can query anything from the
serializer. To have a link, we need the mode... So, as I mentioned in
the other reply, we could define these in some way in the serializer's
properties instead of here, but I'm not sure if that's a good change.

The driver can change the mode at runtime (say, from sync to non-sync
mode, if the HW supports that). But I think this property should reflect
the HW strapped configuration of the serializer.

> Same question for the parameters below. Additionally, are there any
> parameters that need to be identical for all links ?

The same answer to the cdr-mode. No need to be identical.

The strobe-pos and eq-level are unrelated to this topic.

>> +
>> + ti,cdr-mode:
>> + $ref: /schemas/types.yaml#/definitions/uint32
>> + enum:
>> + - 0 # FPD3
>> + - 1 # FPD4
>> + description: FPD-Link CDR Mode
>> +
>> + ti,strobe-pos:
>> + $ref: /schemas/types.yaml#/definitions/int32
>> + minimum: -13
>> + maximum: 13
>> + description: Manual strobe position
>> +
>> + ti,eq-level:
>> + $ref: /schemas/types.yaml#/definitions/uint32
>> + maximum: 14
>> + description: Manual EQ level
>> +
>> + serializer:
>> + type: object
>> + description: FPD-Link Serializer node
>> +
>> + required:
>> + - reg
>> + - i2c-alias
>> + - ti,rx-mode
>> + - serializer
>> +
>> + ports:
>> + $ref: /schemas/graph.yaml#/properties/ports
>> +
>> + properties:
>> + port@0:
>> + $ref: /schemas/graph.yaml#/properties/port
>> + unevaluatedProperties: false
>> + description: FPD-Link input 0
>> +
>> + port@1:
>> + $ref: /schemas/graph.yaml#/properties/port
>> + unevaluatedProperties: false
>> + description: FPD-Link input 1
>> +
>> + port@2:
>> + $ref: /schemas/graph.yaml#/properties/port
>> + unevaluatedProperties: false
>> + description: FPD-Link input 2
>> +
>> + port@3:
>> + $ref: /schemas/graph.yaml#/properties/port
>> + unevaluatedProperties: false
>> + description: FPD-Link input 3
>> +
>> + port@4:
>> + $ref: /schemas/graph.yaml#/$defs/port-base
>> + unevaluatedProperties: false
>> + description: CSI-2 Output 0
>> +
>> + properties:
>> + endpoint:
>> + $ref: /schemas/media/video-interfaces.yaml#
>> + unevaluatedProperties: false
>> +
>> + properties:
>> + data-lanes:
>> + minItems: 1
>> + maxItems: 4
>> +
>> + port@5:
>> + $ref: /schemas/graph.yaml#/$defs/port-base
>> + unevaluatedProperties: false
>> + description: CSI-2 Output 1
>> +
>> + properties:
>> + endpoint:
>> + $ref: /schemas/media/video-interfaces.yaml#
>> + unevaluatedProperties: false
>> +
>> + properties:
>> + data-lanes:
>> + minItems: 1
>> + maxItems: 4
>
> The ports should be mandatory, shouldn't they ?

Did you mean data-lanes? Yes, data-lanes should be mandatory.

Tomi