netdev - Re: [RFC PATCH net-next] net: stmmac: sun8i: drop unneeded default syscon value

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Message-ID: <aAi7tq-otdhJRpTy@Red>
Date: Wed, 23 Apr 2025 12:06:46 +0200
From: Corentin Labbe <clabbe.montjoie@...il.com>
To: Andre Przywara <andre.przywara@....com>
Cc: Andrew Lunn <andrew+netdev@...n.ch>,
	"David S . Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Chen-Yu Tsai <wens@...e.org>,
	Jernej Skrabec <jernej.skrabec@...il.com>,
	Samuel Holland <samuel@...lland.org>, Yixun Lan <dlan@...too.org>,
	Maxime Ripard <mripard@...nel.org>, netdev@...r.kernel.org,
	linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH net-next] net: stmmac: sun8i: drop unneeded default
 syscon value

Le Wed, Apr 23, 2025 at 10:52:22AM +0100, Andre Przywara a écrit :
> For some odd reason we are very picky about the value of the EMAC clock
> register from the syscon block, insisting on a certain reset value and
> only doing read-modify-write operations on that register, even though we
> pretty much know the register layout.
> This already led to a basically redundant variant entry for the H6, which
> only differs by that value. We will have the same situation with the new
> A523 SoC, which again is compatible to the A64, but has a different syscon
> reset value.
> 
> Drop any assumptions about that value, and set or clear the bits that we
> want to program, from scratch (starting with a value of 0). For the
> remove() implementation, we just turn on the POWERDOWN bit, and deselect
> the internal PHY, which mimics the existing code.
> 
> Signed-off-by: Andre Przywara <andre.przywara@....com>
> ---
> Hi,
> 
> if anyone can shed some light on why we had this value and its handling
> in the first place, I would be grateful. I don't really get its purpose,
> and especially the warning message about the reset value seems odd.
> I briefly tested this on A523, H3, H6, but would be glad to see more
> testing on this.
> 

Hello

The origin is me, when doing initial sun8i-emac I feared to miss something and so added some strict tests on its value.
Another goal was to detect half init from firmware/bootloader.

But I agree it is now useless.

I will send this patch on all my CI boards, so you will have extra test.

Acked-by: Corentin LABBE <clabbe.montjoie@...il.com>

Thanks
Regards