netdev - Re: [PATCH] net: stmmac: Fix unset max_speed difference between DT and non-DT platforms

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Date:   Thu, 31 Mar 2022 19:44:31 +0100
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Chen-Yu Tsai <wens@...nel.org>
Cc:     Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Jose Abreu <joabreu@...opsys.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Chen-Yu Tsai <wens@...e.org>,
        netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: stmmac: Fix unset max_speed difference between DT
 and non-DT platforms

On Fri, Apr 01, 2022 at 01:18:27AM +0800, Chen-Yu Tsai wrote:
> From: Chen-Yu Tsai <wens@...e.org>
> 
> In commit 9cbadf094d9d ("net: stmmac: support max-speed device tree
> property"), when DT platforms don't set "max-speed", max_speed is set to
> -1; for non-DT platforms, it stays the default 0.
> 
> Prior to commit eeef2f6b9f6e ("net: stmmac: Start adding phylink support"),
> the check for a valid max_speed setting was to check if it was greater
> than zero. This commit got it right, but subsequent patches just checked
> for non-zero, which is incorrect for DT platforms.

Sounds like it's got to complicated...

> In commit 92c3807b9ac3 ("net: stmmac: convert to phylink_get_linkmodes()")
> the conversion switched completely to checking for non-zero value as a
> valid value, which caused 1000base-T to stop getting advertised by
> default.
> 
> Instead of trying to fix all the checks, simply leave max_speed alone if
> DT property parsing fails.

And this kind of proves that point - if deleting code fixes it...

Acked-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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