Re: [net-next PATCH v10 7/7] rust: net::phy sync with match_phy_device C changes

[Christian Marangi <ansuelsmth@gmail.com>]

On Fri, May 16, 2025 at 04:48:53PM +0200, Benno Lossin wrote:
> On Fri May 16, 2025 at 2:30 PM CEST, FUJITA Tomonori wrote:
> > On Thu, 15 May 2025 13:27:12 +0200
> > Christian Marangi <ansuelsmth@gmail.com> wrote:
> >> @@ -574,6 +577,23 @@ pub const fn create_phy_driver<T: Driver>() -> DriverVTable {
> >>  /// This trait is used to create a [`DriverVTable`].
> >>  #[vtable]
> >>  pub trait Driver {
> >> +    /// # Safety
> >> +    ///
> >> +    /// For the duration of `'a`,
> >> +    /// - the pointer must point at a valid `phy_driver`, and the caller
> >> +    ///   must be in a context where all methods defined on this struct
> >> +    ///   are safe to call.
> >> +    unsafe fn from_raw<'a>(ptr: *const bindings::phy_driver) -> &'a Self
> >> +    where
> >> +        Self: Sized,
> >> +    {
> >> +        // CAST: `Self` is a `repr(transparent)` wrapper around `bindings::phy_driver`.
> >> +        let ptr = ptr.cast::<Self>();
> >> +        // SAFETY: by the function requirements the pointer is valid and we have unique access for
> >> +        // the duration of `'a`.
> >> +        unsafe { &*ptr }
> >> +    }
> >
> > We might need to update the comment. phy_driver is const so I think
> > that we can access to it any time.
> 
> Why is any type implementing `Driver` a transparent wrapper around
> `bindings::phy_driver`?
> 

Is this referred to a problem with using from_raw or more of a general
question on how the rust wrapper are done for phy code?

> >>      /// Defines certain other features this PHY supports.
> >>      /// It is a combination of the flags in the [`flags`] module.
> >>      const FLAGS: u32 = 0;
> >> @@ -602,7 +622,7 @@ fn get_features(_dev: &mut Device) -> Result {
> >>  
> >>      /// Returns true if this is a suitable driver for the given phydev.
> >>      /// If not implemented, matching is based on [`Driver::PHY_DEVICE_ID`].
> >> -    fn match_phy_device(_dev: &Device) -> bool {
> >> +    fn match_phy_device<T: Driver>(_dev: &mut Device, _drv: &T) -> bool {
> >>          false
> >>      }
> >
> > I think that it could be a bit simpler:
> >
> > fn match_phy_device(_dev: &mut Device, _drv: &Self) -> bool
> >
> > Or making it a trait method might be more idiomatic?
> >
> > fn match_phy_device(&self, _dev: &mut Device) -> bool
> 
> Yeah that would make most sense.
>

I think

fn match_phy_device(_dev: &mut Device, _drv: &Self) -> bool

more resemble the C parallel function so I think this suite the best,
should make it easier to port if ever (am I wrong?)

-- 
	Ansuel