linux-kernel - Re: [PATCH v2 2/8] dt-bindings: media: nxp: Add Wave6 video codec device

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Message-ID: <f9eb4322-cf6f-445d-8ba8-39182325ca4e@kernel.org>
Date: Tue, 20 May 2025 08:27:09 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Nas Chung <nas.chung@...psnmedia.com>
Cc: "mchehab@...nel.org" <mchehab@...nel.org>,
 "hverkuil@...all.nl" <hverkuil@...all.nl>, "robh@...nel.org"
 <robh@...nel.org>, "krzk+dt@...nel.org" <krzk+dt@...nel.org>,
 "conor+dt@...nel.org" <conor+dt@...nel.org>,
 "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
 "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "linux-imx@....com" <linux-imx@....com>, "marex@...x.de" <marex@...x.de>,
 "jackson.lee" <jackson.lee@...psnmedia.com>,
 "lafley.kim" <lafley.kim@...psnmedia.com>
Subject: Re: [PATCH v2 2/8] dt-bindings: media: nxp: Add Wave6 video codec
 device

On 19/05/2025 07:08, Nas Chung wrote:
> Hi, Krzysztof.
> 
>> -----Original Message-----
>> From: Krzysztof Kozlowski <krzk@...nel.org>
>> Sent: Friday, May 16, 2025 9:56 PM
>> To: Nas Chung <nas.chung@...psnmedia.com>
>> Cc: mchehab@...nel.org; hverkuil@...all.nl; sebastian.fricke@...labora.com;
>> robh@...nel.org; krzk+dt@...nel.org; conor+dt@...nel.org; linux-
>> media@...r.kernel.org; devicetree@...r.kernel.org; linux-
>> kernel@...r.kernel.org; linux-imx@....com; marex@...x.de; jackson.lee
>> <jackson.lee@...psnmedia.com>; lafley.kim <lafley.kim@...psnmedia.com>
>> Subject: Re: [PATCH v2 2/8] dt-bindings: media: nxp: Add Wave6 video codec
>> device
>>
>> On 13/05/2025 09:39, Nas Chung wrote:
>>>>
>>>> All of above are wrong for the SoC...
>>>>
>>>>>
>>>>>         #include <dt-bindings/interrupt-controller/arm-gic.h>
>>>>>         #include <dt-bindings/clock/nxp,imx95-clock.h>
>>>>>
>>>>>         soc {
>>>>>           #address-cells = <2>;
>>>>>           #size-cells = <2>;
>>>>>
>>>>>           vpu: video-codec {
>>>>>             compatible = "nxp,imx95-vpu", "cnm,wave633c";
>>>>
>>>> What does this device represent? It is not "ctrl", because you made ctrl
>>>> separate device node. Your binding description suggests that is the VPU
>>>> control region.
>>>
>>> My intention was to represent the MMIO VPU device, which includes
>>> both the core and control nodes.
>>
>> Then what is the VPU device if not CTRL? What is the CTRL device?
> 
> The VPU device represents the entire VPU hardware block,
> which includes 1 CTRL component(node) and 4 CORE components(nodes).

What is entire VPU hardware block?

> 
> The CTRL device represents the VCPU, a 32-bit processor embedded within the
> VPU hardware block. This VCPU is responsible for executing the VPU firmware.
> The CTRL device is in charge of tasks such as firmware booting, power management
> (sleep and wakeup command), and managing memory regions that are exclusively
> accessed by the firmware.

This sounds like CTRL is responsible for entire VPU block. What are the
tasks of VPU block then? What are its registers? What is that device
exactly doing?

You keep repeating the same, so my initial idea - CTRL is not a separate
block - still stands. Can you have more CTRL blocks than one?

Best regards,
Krzysztof