Re: [PATCH v2 3/4] nova-core: bitstruct: Add support for custom visiblity

[Alexandre Courbot]

On Mon Sep 8, 2025 at 12:40 PM JST, Alexandre Courbot wrote:
> On Thu Sep 4, 2025 at 6:54 AM JST, Joel Fernandes wrote:
>> Add support for custom visiblity to allow for users to control visibility
>> of the structure and helpers.
>>
>> Signed-off-by: Joel Fernandes <joelagnelf@xxxxxxxxxx>
>> ---
>>  drivers/gpu/nova-core/bitstruct.rs   | 46 ++++++++++++++--------------
>>  drivers/gpu/nova-core/regs/macros.rs | 16 +++++-----
>>  2 files changed, 31 insertions(+), 31 deletions(-)
>>
>> diff --git a/drivers/gpu/nova-core/bitstruct.rs b/drivers/gpu/nova-core/bitstruct.rs
>> index 068334c86981..1047c5c17e2d 100644
>> --- a/drivers/gpu/nova-core/bitstruct.rs
>> +++ b/drivers/gpu/nova-core/bitstruct.rs
>> @@ -9,7 +9,7 @@
>>  ///
>>  /// ```rust
>>  /// bitstruct! {
>> -///     struct ControlReg: u32 {
>> +///     pub struct ControlReg: u32 {
>>  ///         3:0       mode        as u8 ?=> Mode;
>>  ///         7:4       state       as u8 => State;
>>  ///     }
>
> Maybe mention in the documentation that the field accessors are given
> the same visibility as the type - otherwise one might be led into
> thinking that they can specify visibility for individual fields as well
> (I'm wondering whether we might ever want that in the future?).

Answering my own question: it could be useful! One example is
nova-core's `NV_PFALCON_FALCON_HWCFG2::mem_scrubbing` field. It turns
into `0` when scrubbing is completed, which is misleading. So to paliate
that we introduced a `mem_scrubbing_done` method that works as we want,
but the `mem_scrubbing` accessors are still present and can be called by
driver code. Making them private would force all callers to use
`mem_scrubbing_done`.

Another related feature would be a way to make some fields read-only or
write-only through an optional parameter.

I'm just mentioning these for the record; I'm not suggesting they need
to be done for the current series. :)