Re: [PATCH v4 08/15] dt-bindings: dma: ti: Add document for K3 UDMA

Peter Ujfalusi
2019-11-26T08:29:42Z

Rob,

On 15/11/2019 11.45, Peter Ujfalusi wrote:
> Rob,
>
> On 14/11/2019 19.53, Rob Herring wrote:
>> On Tue, Nov 5, 2019 at 4:07 AM Peter Ujfalusi <peter.ujfalusi@ti.com> wrote:
>>>
>>>
>>>
>>> On 05/11/2019 4.19, Rob Herring wrote:
>>>> On Fri, Nov 01, 2019 at 10:41:28AM +0200, Peter Ujfalusi wrote:
>>>>> New binding document for
>>>>> Texas Instruments K3 NAVSS Unified DMA – Peripheral Root Complex (UDMA-P).
>>>>>
>>>>> UDMA-P is introduced as part of the K3 architecture and can be found in
>>>>> AM654 and j721e.
>>>>>
>>>>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
>>>>> ---
>>>>> Rob,
>>>>>
>>>>> can you give me some hint on how to fix these two warnings from dt_binding_check:
>>>>>
>>>>> DTC Documentation/devicetree/bindings/dma/ti/k3-udma.example.dt.yaml
>>>>> Documentation/devicetree/bindings/dma/ti/k3-udma.example.dts:23.13-72: Warning (ranges_format): /example-0/interconnect@30800000:ranges: "ranges" property has invalid length (24 bytes) (parent #address-cells == 1, child #address-cells == 2, #size-cells == 2)
>>>>> CHECK Documentation/devicetree/bindings/dma/ti/k3-udma.example.dt.yaml
>>>>
>>>> The default #address-cells is 1 for examples. So you need to
>>>> either override it or change ranges parent address size.
>>>
>>> wrapping the cbass_main_navss inside:
>>> cbass_main {
>>> #address-cells = <2>;
>>> #size-cells = <2>;
>>> ...
>>> };
>>>
>>> fixes it.
>>>
>>>>>
>>>>> Documentation/devicetree/bindings/dma/ti/k3-udma.example.dt.yaml: interconnect@30800000: $nodename:0: 'interconnect@30800000' does not match '^(bus|soc|axi|ahb|apb)(@[0-9a-f]+)?$'
>>>>
>>>> Use 'bus' for the node name of 'simple-bus'.
>>>
>>> I took the navss node from the upstream dts (I'm going to fix it there
>>> as well).
>>> It has simple-bus for the navss, which is not quite right as NAVSS is
>>> not a bus, but a big subsystem with multiple components (UDMAP, ringacc,
>>> INTA, INTR, timers, etc).
>>>
>>> What about to change the binding doc to simple-mfd like this
>>
>> That's really for things not memory-mapped (I'm sure you can probably
>> find an example to contradict me), so better to keep simple-bus if all
>> the child nodes have addresses.
>
> According to Documentation/devicetree/bindings/mfd/mfd.txt:
> - A range of memory registers containing "miscellaneous system
> registers" also known as a system controller "syscon" or any other
> memory range containing a mix of unrelated hardware devices.
>
> NAVSS (NAVigator SubSystem) falls in the later case, it contains
> unrelated blocks, like the UDMAP, ringacc, mailboxes, spinlocks,
> interrupt aggregator, interrupt router, etc.
>
> - compatible : "simple-mfd" - this signifies that the operating system
> should consider all subnodes of the MFD device as separate devices
> akin to how "simple-bus" indicates when to see subnodes as children
> for a simple memory-mapped bus.
>
> This is a bit confusing, but NAVSS is not really a bus, everything in it
> can be accessed by the CPU via memory mapped registers (some sub devices
> does not have registers defined, they are controlled via system firmware).
>
>> Do you need the node name to be 'navss' for some reason? If so, then
>> better have a compatible string in there to identify it. If not, just
>> use 'bus' and be done with it.
>
> We don't need unique compatible for the NAVSS itself as there is not
> much we can configure on the top level, it is 'just' a big subsystem
> with all sorts of things.
>
> I like to keep the 'navss' as node name as it gives human understandable
> representation of it in /sys for example, easier to see the topology.
>
> I just feel that the 'bus' does not really apply to what NAVSS is.
> Probably my view of simple-bus is not correct.

Can you advice on how to proceed? I would like to send v6 so Vinod can
pick it for next after 5.5-rc1 is tagged.
This is the only thing which I need to close on to be able to do that.

>
>>> cbass_main_navss: navss@30800000 {
>>> compatible = "simple-mfd";
>>> #address-cells = <2>;
>>> #size-cells = <2>;
>>> ...
>>> };
>>>
>>> and fix up the DT when I got to the point when I can send the patches to
>>> enable DMA for am654 and j721e?
>>
>> There's no requirement yet for DTS files to not have warnings.
>
> Sure, but it does not hurt if they are clean ;)
>
>>>>> + compatible:
>>>>> + oneOf:
>>>>> + - const: ti,am654-navss-main-udmap
>>>>> + - const: ti,am654-navss-mcu-udmap
>>>>> + - const: ti,j721e-navss-main-udmap
>>>>> + - const: ti,j721e-navss-mcu-udmap
>>>>
>>>> enum works better than oneOf+const. Better error messages.
>>>
>>> Like this:
>>> compatible:
>>> oneOf:
>>> - description: for AM654
>>> items:
>>> - enum:
>>> - ti,am654-navss-main-udmap
>>> - ti,am654-navss-mcu-udmap
>>>
>>> - description: for J721E
>>> items:
>>> - enum:
>>> - ti,j721e-navss-main-udmap
>>> - ti,j721e-navss-mcu-udmap
>>
>> If the 'description' was useful, but it's not. Just:
>>
>> compatible:
>> enum:
>> - ti,am654-navss-main-udmap
>> - ti,am654-navss-mcu-udmap
>> - ti,j721e-navss-main-udmap
>> - ti,j721e-navss-mcu-udmap
>
> OK, can I keep your Reviewed-by you have given to v5 if I do this change
> for v6?
>
>>
>>
>> Rob
>>
>
> - Péter
>
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- Péter