Nouveau - Nov 2025 - [PATCH v6 1/4] gpu: nova-core: implement Display for Spec

On Fri, 2025-11-07 at 20:39 -0800, John Hubbard wrote:
> Implement Display for Spec. This simplifies the dev_info!() code for
> printing banners such as:
> 
> ??? NVIDIA (Chipset: GA104, Architecture: Ampere, Revision: a.1)
> 
> Cc: Alexandre Courbot <acourbot at nvidia.com>
> Cc: Danilo Krummrich <dakr at kernel.org>
> Cc: Timur Tabi <ttabi at nvidia.com>
> Signed-off-by: John Hubbard <jhubbard at nvidia.com>
I'm okay with the entire patch set, but I do have a few questions.
> +impl fmt::Display for Spec {
> +??? fn fmt(&self, f: &mut fmt::Formatter<'_>) ->
fmt::Result {
> +??????? write!(
> +??????????? f,
> +??????????? "Chipset: {}, Architecture: {:?}, Revision: {}",
> +??????????? self.chipset,
> +??????????? self.chipset.arch(),
> +??????????? self.revision
> +??????? )
> +??? }
> +}
> +
> ?/// Structure holding the resources required to operate the GPU.
> ?#[pin_data]
> ?pub(crate) struct Gpu {
> @@ -206,13 +218,7 @@ pub(crate) fn new<'a>(
> ???? ) -> impl PinInit<Self, Error> + 'a {
> ???????? try_pin_init!(Self {
> ???????????? spec: Spec::new(bar).inspect(|spec| {
> -??????????????? dev_info!(
> -??????????????????? pdev.as_ref(),
> -??????????????????? "NVIDIA (Chipset: {}, Architecture: {:?},
Revision: {})\n",
> -??????????????????? spec.chipset,
> -??????????????????? spec.chipset.arch(),
> -??????????????????? spec.revision
> -??????????????? );
> +??????????????? dev_info!(pdev.as_ref(),"NVIDIA ({})\n", spec);
I believe that this is the only place where a `Spec` is actually printed.  Does
it really make
sense to implement Display for a single usage?  Do we generally want to
implement Display for
new types?

On 11/7/25 9:02 PM, Timur Tabi wrote:
> On Fri, 2025-11-07 at 20:39 -0800, John Hubbard wrote:
>> Implement Display for Spec. This simplifies the dev_info!() code for
>> printing banners such as:
>>
>> ??? NVIDIA (Chipset: GA104, Architecture: Ampere, Revision: a.1)
>>
>> Cc: Alexandre Courbot <acourbot at nvidia.com>
>> Cc: Danilo Krummrich <dakr at kernel.org>
>> Cc: Timur Tabi <ttabi at nvidia.com>
>> Signed-off-by: John Hubbard <jhubbard at nvidia.com>
> 
> I'm okay with the entire patch set, but I do have a few questions.
Great!
> 
>> +impl fmt::Display for Spec {
>> +??? fn fmt(&self, f: &mut fmt::Formatter<'_>) ->
fmt::Result {
>> +??????? write!(
>> +??????????? f,
>> +??????????? "Chipset: {}, Architecture: {:?}, Revision: {}",
>> +??????????? self.chipset,
>> +??????????? self.chipset.arch(),
>> +??????????? self.revision
>> +??????? )
>> +??? }
>> +}
>> +
>> ?/// Structure holding the resources required to operate the GPU.
>> ?#[pin_data]
>> ?pub(crate) struct Gpu {
>> @@ -206,13 +218,7 @@ pub(crate) fn new<'a>(
>> ???? ) -> impl PinInit<Self, Error> + 'a {
>> ???????? try_pin_init!(Self {
>> ???????????? spec: Spec::new(bar).inspect(|spec| {
>> -??????????????? dev_info!(
>> -??????????????????? pdev.as_ref(),
>> -??????????????????? "NVIDIA (Chipset: {}, Architecture: {:?},
Revision: {})\n",
>> -??????????????????? spec.chipset,
>> -??????????????????? spec.chipset.arch(),
>> -??????????????????? spec.revision
>> -??????????????? );
>> +??????????????? dev_info!(pdev.as_ref(),"NVIDIA ({})\n",
spec);
> 
> I believe that this is the only place where a `Spec` is actually printed. 
Does it really make
> sense to implement Display for a single usage?  Do we generally want to
implement Display for
> new types?
> 
I agree that it looks a little excessive, but I defer to reviewers
who have a lot more Rust experience, and they requested this during
a review of an earlier version.


thanks,
-- 
John Hubbard