Re: [PATCH v5 03/14] gpu: nova-core: gsp: Create wpr metadata

["Danilo Krummrich" <dakr@kernel.org>]

On Fri Oct 17, 2025 at 1:03 AM CEST, Alistair Popple wrote:
> On 2025-10-16 at 17:23 +1100, Alexandre Courbot <acourbot@nvidia.com> wrote...
>> On Mon Oct 13, 2025 at 3:20 PM JST, Alistair Popple wrote:
>> > +impl GspFwWprMeta {
>> > +    pub(crate) fn new(gsp_firmware: &GspFirmware, fb_layout: &FbLayout) -> Self {
>> > +        Self(bindings::GspFwWprMeta {
>> > +            magic: r570_144::GSP_FW_WPR_META_MAGIC as u64,
>> > +            revision: u64::from(r570_144::GSP_FW_WPR_META_REVISION),
>> > +            sysmemAddrOfRadix3Elf: gsp_firmware.radix3_dma_handle(),
>> > +            sizeOfRadix3Elf: gsp_firmware.size as u64,
>> 
>> Very unfortunately I'm afraid we will need to replace the `as` in this
>> method with `u64::try_from` and make it return a `Result` for now.
>
> And presumably most of the other `as` keywords in this function dealing with
> usize as well? Have made the change but would you mind quickly explaining
> why this is needed? Is the concern that usize might be more than 64 bits or
> something?

Since nova-core depends on CONFIG_64BIT, I think we want a helper function that
converts usize to u64 infallibly.

This helper function can simply generate a compile time error, when
!CONFIG_64BIT, etc.

We can do this locally in nova-core, but it could also find it's place in the
generic infrastructure. nova-core clearly won't be the last driver running into
this inconvinience.