On Sat, 28 Oct 2023 18:45:40 +0000
Benno Lossin [off-list ref] wrote:

On 28.10.23 20:23, Andrew Lunn wrote:

quoted

On Sat, Oct 28, 2023 at 04:37:53PM +0000, Benno Lossin wrote:

quoted

On 28.10.23 11:27, FUJITA Tomonori wrote:

quoted

On Fri, 27 Oct 2023 21:19:38 +0000
Benno Lossin [off-list ref] wrote:

quoted

I did not notice this before, but this means we cannot use the `link`
function from bindgen, since that takes `&self`. We would need a
function that takes `*const Self` instead.

Implementing functions to access to a bitfield looks tricky so we need
to add such feature to bindgen or we add getters to the C side?

Indeed, I just opened an issue [1] on the bindgen repo.

[1]: https://github.com/rust-lang/rust-bindgen/issues/2674

Please could you help me understand the consequences here. Are you
saying the rust toolchain is fatally broken here, it cannot generate
valid code at the moment? As a result we need to wait for a new
version of bindgen?

This only affects bitfields, since they require special accessor functions
generated by bindgen, so I would not say that the toolchain is fatally broken.
It also is theoretically possible to manually access the bitfields in a correct
manner, but that is error prone (which is why we use the accessor functions
provided by bindgen).

In this particular case we have three options:
1. wait until bindgen provides a raw accessor function that allows to use
    only raw pointers.
2. create some C helper functions for the bitfield access that will be replaced
    by the bindgen functions once bindgen has updated.
3. Since for the `phy_device` bindings, we only ever call functions while holding
    the `phy_device.lock` lock (at least I think that this is correct) we might be
    able to get away with creating a reference to the object and use the current
    accessor functions anyway.

But for point 3 I will have to consult the others.

The current code is fine from Rust perspective because the current
code copies phy_driver on stack and makes a reference to the copy, if
I undertand correctly.

It's not nice to create an 500-bytes object on stack. It turned out
that it's not so simple to avoid it.