Re: [PATCH RFC v2 1/3] gpu: nova-core: register: use field type for Into implementation

["Alexandre Courbot" <acourbot@nvidia.com>]

On Fri Oct 10, 2025 at 5:24 PM JST, Alexandre Courbot wrote:
> On Fri Oct 10, 2025 at 12:41 AM JST, Joel Fernandes wrote:
>>
>>
>>> On Oct 9, 2025, at 11:17 AM, Joel Fernandes <joelagnelf@nvidia.com> wrote:
>>> 
>>> Hi Alex,
>>> 
>>>> On 10/9/2025 8:37 AM, Alexandre Courbot wrote:
>>>> The getter method of a field works with the field type, but its setter
>>>> expects the type of the register. This leads to an asymmetry in the
>>>> From/Into implementations required for a field with a dedicated type.
>>>> For instance, a field declared as
>>>> 
>>>>    pub struct ControlReg(u32) {
>>>>        3:0 mode as u8 ?=> Mode;
>>>>        ...
>>>>    }
>>>> 
>>>> currently requires the following implementations:
>>>> 
>>>>    impl TryFrom<u8> for Mode {
>>>>      ...
>>>>    }
>>>> 
>>>>    impl From<Mode> for u32 {
>>>>      ...
>>>>    }
>>>> 
>>>> Change this so the `From<Mode>` now needs to be implemented for `u8`,
>>>> i.e. the primitive type of the field. This is more consistent, and will
>>>> become a requirement once we start using the TryFrom/Into derive macros
>>>> to implement these automatically.
>>>> 
>>>> Reported-by: Edwin Peer <epeer@nvidia.com>
>>>> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
>>> 
>>> As these are incremental improvements, could you please rebase on top of the v6
>>> bitfield series so it does not conflict?
>>> 
>>> https://git.kernel.org/pub/scm/linux/kernel/git/jfern/linux.git/log/?h=nova.dev.bitfield.submitted.v6
>>
>> On second thought, I could just carry this patch on top of my v6 series and avoid too much conflict.
>>
>> So if it is ok with you, please only carry the last 2 patches of this series whenever applying.
>>
>> For this patch:
>> Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
>>
>> I will review the other two patches as well. Thanks.
>
> The idea is for this patch to go *before* your series, to avoid the
> asymmetry in the From/Into implementions of bitfields. We could also put
> it after, but it would become larger as a result and I think it can be
> merge soon after -rc1 is tagged anyway.

I forgot to mention that this patch is not really part of the series ;
it's just here to allow it to apply on top of drm-rust-next should
anyone want to try it.