netdev - Re: [PATCH net-next v1 2/2] net: phy: qt2025: wait until PHY becomes ready

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Message-ID: <CAH5fLghAC76mZ0WQVg6U9rZxe6Nz0Y=2mgDNzVw9FzwpuXDb2Q@mail.gmail.com>
Date: Tue, 1 Oct 2024 13:36:41 +0200
From: Alice Ryhl <aliceryhl@...gle.com>
To: FUJITA Tomonori <fujita.tomonori@...il.com>
Cc: netdev@...r.kernel.org, rust-for-linux@...r.kernel.org, andrew@...n.ch, 
	hkallweit1@...il.com, tmgross@...ch.edu, ojeda@...nel.org, 
	alex.gaynor@...il.com, gary@...yguo.net, bjorn3_gh@...tonmail.com, 
	benno.lossin@...ton.me, a.hindborg@...sung.com
Subject: Re: [PATCH net-next v1 2/2] net: phy: qt2025: wait until PHY becomes ready

On Tue, Oct 1, 2024 at 1:27 PM FUJITA Tomonori
<fujita.tomonori@...il.com> wrote:
>
> Wait until a PHY becomes ready in the probe callback by using a sleep
> function.
>
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@...il.com>
> ---
>  drivers/net/phy/qt2025.rs | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/phy/qt2025.rs b/drivers/net/phy/qt2025.rs
> index 28d8981f410b..3a8ef9f73642 100644
> --- a/drivers/net/phy/qt2025.rs
> +++ b/drivers/net/phy/qt2025.rs
> @@ -93,8 +93,15 @@ fn probe(dev: &mut phy::Device) -> Result<()> {
>          // The micro-controller will start running from SRAM.
>          dev.write(C45::new(Mmd::PCS, 0xe854), 0x0040)?;
>
> -        // TODO: sleep here until the hw becomes ready.
> -        Ok(())
> +        // sleep here until the hw becomes ready.
> +        for _ in 0..60 {
> +            kernel::delay::sleep(core::time::Duration::from_millis(50));
> +            let val = dev.read(C45::new(Mmd::PCS, 0xd7fd))?;
> +            if val != 0x00 && val != 0x10 {
> +                return Ok(());
> +            }

Why not place the sleep after this check? That way, we don't need to
sleep if the check succeeds immediately.

> +        }
> +        Err(code::ENODEV)

This sleeps for up to 3 seconds. Is that the right amount to sleep?

Alice