netdev - Re: [PATCH v3 1/3] net: stmmac: socfpga: add call to assert/deassert ahb reset line

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Message-ID: <1fe08251f091bd695f630b7b46ae8c8d85d664a3.camel@pengutronix.de>
Date: Thu, 08 Jan 2026 14:22:48 +0100
From: Philipp Zabel <p.zabel@...gutronix.de>
To: Dinh Nguyen <dinguyen@...nel.org>, Maxime Chevallier	
 <maxime.chevallier@...tlin.com>, 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>, Maxime Coquelin <mcoquelin.stm32@...il.com>, Alexandre
 Torgue	 <alexandre.torgue@...s.st.com>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Mamta Shukla	 <mamta.shukla@...ca-geosystems.com>,
 Ahmad Fatoum <a.fatoum@...gutronix.de>
Cc: bsp-development.geo@...ca-geosystems.com, Pengutronix Kernel Team	
 <kernel@...gutronix.de>, netdev@...r.kernel.org, 
	linux-stm32@...md-mailman.stormreply.com,
 linux-arm-kernel@...ts.infradead.org, 	linux-kernel@...r.kernel.org,
 devicetree@...r.kernel.org
Subject: Re: [PATCH v3 1/3] net: stmmac: socfpga: add call to
 assert/deassert ahb reset line

On Do, 2026-01-08 at 07:08 -0600, Dinh Nguyen wrote:
> The "stmmaceth-ocp" reset line of stmmac controller on the SoCFPGA
> platform is essentially the "ahb" reset on the standard stmmac
> controller. But since stmmaceth-ocp has already been introduced into
> the wild, we cannot just remove support for it. But what we can do is
> to support both "stmmaceth-ocp" and "ahb" reset names. Going forward we
> will be using "ahb", but in order to not break ABI, we will be call reset
> assert/de-assert both ahb and stmmaceth-ocp.
> 
> The ethernet hardware on SoCFPGA requires either the stmmaceth-ocp or
> ahb reset to be asserted every time before changing the phy mode, then
> de-asserted when the phy mode has been set.
> 
> With this change, we should be able to revert patch:
> commit 62a40a0d5634 ("arm: dts: socfpga: use reset-name "stmmaceth-ocp"
> instead of "ahb"")
> 
> Signed-off-by: Dinh Nguyen <dinguyen@...nel.org>
> ---
>  drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c
> index a2b52d2c4eb6f..79df55515c718 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c
> @@ -407,6 +407,7 @@ static int socfpga_gen5_set_phy_mode(struct socfpga_dwmac *dwmac)
>  
>  	/* Assert reset to the enet controller before changing the phy mode */
>  	reset_control_assert(dwmac->stmmac_ocp_rst);
> +	reset_control_assert(dwmac->plat_dat->stmmac_ahb_rst);

Since these two are just different names for the same reset,
I think it would be cleaner to rename dwmac->stmmac_ocp_rst to
dwmac->stmmac_ahb_rst and assign this either to
dwmac->plat_dat->stmmac_ahb_rst or to the stmmac-ocp reset during
probe.

Also, a comment explaining that the dem_reset_control_get_optional(dev,
"stmmaceth-ocp") is for backwards compatibility with legacy device
trees could be helpful to future readers.


regards
Philipp