Re: [PATCH 1/3] dt-bindings: media: mali-c55: Allow wakeup source

[Linus Walleij]

On Wed, Oct 7, 2026 at 11:29 AM Dan Scally <dan.scally@xxxxxxxxxxxxxxxx> wrote:

> On 29/09/2026 13:02, Linus Walleij wrote:
> > The Mali-C55 interrupt can be wired as a wake source on platforms that
> > support it. Use the standard wakeup-source property.
>
> That's interesting! How's that work, though? In the RZ/V2H particularly the ISP is in an offline
> mode, so I'm struggling to see how one could trigger the interrupt whilst the device is suspended,
> since you'd need to instruct the IVC to queue a frame.

The implementation is IP-neutral and doesn't really ask this question.

The typical silicon solution would be if the IP was synthesized into
and always-on power domain on the chip. This means the CPU
which runs Linux is powered off, while the ISP is still powered
on, and could generate a wakeup IRQ. This is how e.g. GPIO
units that can wake up the system work: they are always
powered in some sense.

I don't know if that makes any *sense* from a system engineering
point of view, but it is something that can be done.

Yours,
Linus Walleij