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Date: Wed, 18 Oct 2023 22:27:55 +0200
From: Andrew Lunn <andrew@lunn.ch>
To: FUJITA Tomonori <fujita.tomonori@gmail.com>
Cc: netdev@vger.kernel.org, rust-for-linux@vger.kernel.org,
	miguel.ojeda.sandonis@gmail.com, tmgross@umich.edu,
	boqun.feng@gmail.com, wedsonaf@gmail.com, benno.lossin@proton.me,
	greg@kroah.com
Subject: Re: [PATCH net-next v5 1/5] rust: core abstractions for network PHY
 drivers
Message-ID: <de9d1b30-ab19-44f9-99a3-073c6d2b36e1@lunn.ch>
References: <20231017113014.3492773-1-fujita.tomonori@gmail.com>
 <20231017113014.3492773-2-fujita.tomonori@gmail.com>
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In-Reply-To: <20231017113014.3492773-2-fujita.tomonori@gmail.com>

> +    /// Reads a given C22 PHY register.
> +    pub fn read(&mut self, regnum: u16) -> Result<u16> {
> +        let phydev = self.0.get();
> +        // SAFETY: `phydev` is pointing to a valid object by the type invariant of `Self`.
> +        // So an FFI call with a valid pointer.
> +        let ret = unsafe {
> +            bindings::mdiobus_read((*phydev).mdio.bus, (*phydev).mdio.addr, regnum.into())

If i've understood the discussion about &mut, it is not needed here,
and for write. Performing a read/write does not change anything in
phydev. There was mention of statistics, but they are in the mii_bus
structure, which is pointed to by this structure, but is not part of
this structure.

> +        };
> +        if ret < 0 {
> +            Err(Error::from_errno(ret))
> +        } else {
> +            Ok(ret as u16)
> +        }
> +    }
> +
> +    /// Writes a given C22 PHY register.
> +    pub fn write(&mut self, regnum: u16, val: u16) -> Result {
> +        let phydev = self.0.get();
> +        // SAFETY: `phydev` is pointing to a valid object by the type invariant of `Self`.
> +        // So an FFI call with a valid pointer.
> +        to_result(unsafe {
> +            bindings::mdiobus_write((*phydev).mdio.bus, (*phydev).mdio.addr, regnum.into(), val)
> +        })
> +    }
> +
> +    /// Reads a paged register.
> +    pub fn read_paged(&mut self, page: u16, regnum: u16) -> Result<u16> {

>From my reading of the code, read_paged also does not modify phydev.

     Andrew