Re: [PATCH v10 08/28] gpu: nova-core: Blackwell: calculate reserved FB heap size

[Alexandre Courbot]

On Sat Apr 11, 2026 at 11:49 AM JST, John Hubbard wrote:
<snip>
> @@ -168,6 +175,8 @@ pub(crate) struct FbLayout {
>      pub(crate) wpr2: FbRange,
>      pub(crate) heap: FbRange,
>      pub(crate) vf_partition_count: u8,
> +    /// PMU reserved memory size, in bytes.
> +    pub(crate) pmu_reserved_size: u32,
>  }
>  
>  impl FbLayout {
> @@ -268,6 +277,29 @@ pub(crate) fn new(chipset: Chipset, bar: &Bar0, gsp_fw: &GspFirmware) -> Result<
>              wpr2,
>              heap,
>              vf_partition_count: 0,
> +            pmu_reserved_size: match chipset.arch() {
> +                Architecture::BlackwellGB10x | Architecture::BlackwellGB20x => PMU_RESERVED_SIZE,
> +                _ => 0,
> +            },

I suspect you can just call `calc_pmu_reserved_size`, which seem to
perform the exact same computation?

>          })
>      }
>  }
> +
> +/// Returns the PMU reserved memory size for `chipset`.
> +#[expect(dead_code)]
> +pub(crate) fn calc_pmu_reserved_size(chipset: Chipset) -> u32 {
> +    match chipset.arch() {
> +        Architecture::BlackwellGB10x | Architecture::BlackwellGB20x => PMU_RESERVED_SIZE,
> +        _ => 0,
> +    }

We should avoid these matches on Architecture in common code as much as
possible - that's what the HALs are for. Which means that
`calc_pmu_reserved_size` should call a HAL method to obtain the right
size (I'd also rename it to just `pmu_reserved_size` as we are not
computing anything at runtime).

> +}
> +
> +/// PMU reserved size, aligned to 128KB.
> +pub(crate) const PMU_RESERVED_SIZE: u32 = usize_into_u32::<
> +    {
> +        match const_align_up(SZ_8M + SZ_16M + SZ_4K, Alignment::new::<SZ_128K>()) {
> +            Some(v) => v,
> +            None => panic!("PMU_RESERVED_SIZE: alignment overflow"),
> +        }
> +    },
> +>();

Consequently, this should be moved into the Blackwell HAL - which is
where is belongs, as contrary to what its name implies in the current
module, this reserved size does not apply to all architectures.