[PATCH] drm/panfrost: Dynamically allocate pm_domains

[Rob Herring]

On Mon, Feb 14, 2022 at 2:31 PM Alyssa Rosenzweig
<alyssa.rosenzweig at collabora.com> wrote:
>
> MT8192 requires 5 power domains. Rather than bump MAX_PM_DOMAINS and
> waste memory on every supported Panfrost chip, instead dynamically
> allocate pm_domain_devs and pm_domain_links. This adds some flexibility;
> it seems inevitable a new MediaTek device will require more than 5
> domains.
>
> On non-MediaTek devices, this saves a small amount of memory.

How much? You measured it?

It's not that simple. kmalloc has finite allocation sizes (see
/proc/slabinfo). So unless panfrost_device shrinks or grows to the
next smaller or larger size, the memory used doesn't change. And each
devm_kmalloc adds its own overhead as well.

I'd do the oneliner changing it to 5 and be done with it. That being
said, we have plenty of examples of doing this both ways, so whatever
makes people happy.

Rob