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SubjectRe: [PATCH] dt-bindings: mailbox: mtk-gce: Convert txt to json-schema
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Il 20/05/22 10:15, Krzysztof Kozlowski ha scritto:
> On 19/05/2022 12:18, AngeloGioacchino Del Regno wrote:
>> Convert the mtk-gce documentation from freeform text format to a
>> json-schema.
>>
>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
>> ---
>> .../bindings/mailbox/mediatek,gce-mbox.yaml | 114 ++++++++++++++++++
>> .../devicetree/bindings/mailbox/mtk-gce.txt | 82 -------------
>> 2 files changed, 114 insertions(+), 82 deletions(-)
>> create mode 100644 Documentation/devicetree/bindings/mailbox/mediatek,gce-mbox.yaml
>> delete mode 100644 Documentation/devicetree/bindings/mailbox/mtk-gce.txt
>>
>> diff --git a/Documentation/devicetree/bindings/mailbox/mediatek,gce-mbox.yaml b/Documentation/devicetree/bindings/mailbox/mediatek,gce-mbox.yaml
>> new file mode 100644
>> index 000000000000..750391b4038c
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/mailbox/mediatek,gce-mbox.yaml
>> @@ -0,0 +1,114 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/mailbox/mediatek,gce-mbox.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: MediaTek Global Command Engine (GCE) mailbox
>> +
>> +maintainers:
>> + - Houlong Wei <houlong.wei@mediatek.com>
>> +
>> +description: |
>> + The Global Command Engine (GCE) is used to help read/write registers
>> + with critical time limitation, such as updating display configuration
>> + during the vblank.
>> + The GCE can be used to implement the Command Queue (CMDQ) driver.
>
> Mention the headers in description.
>

Values for properties used by the GCE, such as sub-system IDs, thread

priority and event IDs are defined in 'dt-bindings/gce/<chip>-gce.h'.

Would that be enough, or should I list all of the headers?

>> +
>> +properties:
>> + compatible:
>> + enum:
>> + - mediatek,mt6779-gce
>> + - mediatek,mt8173-gce
>> + - mediatek,mt8183-gce
>> + - mediatek,mt8186-gce
>> + - mediatek,mt8192-gce
>> + - mediatek,mt8195-gce
>> +
>> + reg:
>> + maxItems: 1
>> +
>> + interrupts:
>> + maxItems: 1
>> +
>> + clocks:
>> + maxItems: 1
>> +
>> + clock-names:
>> + items:
>> + - const: gce
>> +
>> + '#mbox-cells':
>> + description: |
>> + The first cell describes the mailbox channel, which is the GCE Thread ID;
>> + The second cell describes the priority of the GCE thread.
>> + const: 2
>> +
>> +required:
>> + - compatible
>> + - reg
>> + - interrupts
>> + - clocks
>> + - clock-names
>> + - '#mbox-cells'
>> +
>> +additionalProperties: false
>> +
>> +allOf:
>> + - if:
>> + properties:
>> + compatible:
>> + enum:
>> + - mediatek,mt8195-gce
>> + then:
>> + properties:
>> + clocks:
>> + maxItems: 2
>
> Are you sure this works on mt8195-gce?
>

Thanks for that, I've just rechecked the driver and.. no, that won't
work for MT8195: it's just one clock there (like the others) and the
clock names aren't even enforced, as the driver is always taking the
clock at index 0.

I got confused because the driver uses a slightly different kind of
logic when probing on SoCs with multiple mailboxes, specifically:
- For single mailbox, having a clock with name "gce" is enforced
as it's grabbing it with devm_clk_get(dev, clk_name), where the
clock name is declared in a string called "clk_name";
- For multiple mailboxes, it's looking for an of_alias, declared
in an array of strings called "clk_names" and getting the clock
with of_clk_get(node, 0).


So there comes my confusion, recapping:

static const char * const clk_name = "gce";
<- this is a clock name
static const char * const clk_names[] = { "gce0", "gce1" }; <- OF alias names


At this point, I think that the best idea would be to fix this issue
first... luckily there's no MT8195 devicetree upstream yet, so I would
technically not be breaking any ABI by changing it to be the same as
the others.

Easier explanation: plan is to change the driver such that we won't
need anything different from the others in this schema.

New version coming soon, then....

Regards,
Angelo

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