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Date:   Tue, 28 Nov 2023 18:26:41 +0100
From:   Maxime Chevallier <maxime.chevallier@bootlin.com>
To:     Andrew Lunn <andrew@lunn.ch>
Cc:     davem@davemloft.net, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, thomas.petazzoni@bootlin.com,
        Jakub Kicinski <kuba@kernel.org>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>,
        linux-arm-kernel@lists.infradead.org,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Jose Abreu <joabreu@synopsys.com>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Simon Horman <horms@kernel.org>,
        linux-stm32@st-md-mailman.stormreply.com,
        alexis.lothore@bootlin.com
Subject: Re: [PATCH net] net: stmmac: dwmac-socfpga: Don't access SGMII
 adapter when not available
Message-ID: <20231128182641.7e2363c0@device.home>
In-Reply-To: <50d318fd-a82c-4756-a349-682b867c0b8b@lunn.ch>
References: <20231128094538.228039-1-maxime.chevallier@bootlin.com>
        <50d318fd-a82c-4756-a349-682b867c0b8b@lunn.ch>
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Hi Andrew,

On Tue, 28 Nov 2023 17:37:30 +0100
Andrew Lunn <andrew@lunn.ch> wrote:

> On Tue, Nov 28, 2023 at 10:45:37AM +0100, Maxime Chevallier wrote:
> > The SGMII adapter isn't present on all dwmac-socfpga implementations.
> > Make sure we don't try to configure it if we don't have this adapter.  
> 
> If it does not exist, why even try to call socfpga_sgmii_config()?
> 
> It seems like this test needs moving up the call stack. socfpga_gen5_set_phy_mode():
> 
> 	if (phymode == PHY_INTERFACE_MODE_SGMII)
> 		if (dwmac->sgmii_adapter_base)
> 			socfpga_sgmii_config(dwmac, true);
> 		else
> 			return -EINVAL;

I don't have access to a platform with the SGMII adapter available, but
my understanding is that we shouldn't error-out when we don't have the
adapter, as some other component (like the lynx PCS) might be there to
handle that mode.

However you have a valid point in that we might want to check if we
have either an SGMII adapter or a PCS, and if we have none of these we
error-out. Thanks for the suggestion, I'll address that :)

Maxime