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Message-ID: <956792db-c6a4-f16f-e7e4-b9d08c12f986@gmail.com>
Date:   Wed, 5 Apr 2023 05:30:09 -0700
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Subject: Re: [PATCH 05/12] net: phy: add phy_id_broken support
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To:     Andrew Lunn <andrew@lunn.ch>,
        Marco Felsch <m.felsch@pengutronix.de>
Cc:     Heiner Kallweit <hkallweit1@gmail.com>,
        Russell King <linux@armlinux.org.uk>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@broadcom.com>,
        Richard Cochran <richardcochran@gmail.com>,
        Radu Pirea <radu-nicolae.pirea@oss.nxp.com>,
        Shyam Sundar S K <Shyam-sundar.S-k@amd.com>,
        Yisen Zhuang <yisen.zhuang@huawei.com>,
        Salil Mehta <salil.mehta@huawei.com>,
        Jassi Brar <jaswinder.singh@linaro.org>,
        Ilias Apalodimas <ilias.apalodimas@linaro.org>,
        Iyappan Subramanian <iyappan@os.amperecomputing.com>,
        Keyur Chudgar <keyur@os.amperecomputing.com>,
        Quan Nguyen <quan@os.amperecomputing.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Len Brown <lenb@kernel.org>, Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org,
        devicetree@vger.kernel.org, kernel@pengutronix.de
References: <20230405-net-next-topic-net-phy-reset-v1-0-7e5329f08002@pengutronix.de>
 <20230405-net-next-topic-net-phy-reset-v1-5-7e5329f08002@pengutronix.de>
 <6461467c-8f9d-41b6-b060-08190126e81f@lunn.ch>
From:   Florian Fainelli <f.fainelli@gmail.com>
In-Reply-To: <6461467c-8f9d-41b6-b060-08190126e81f@lunn.ch>
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On 4/5/2023 5:27 AM, Andrew Lunn wrote:
> On Wed, Apr 05, 2023 at 11:26:56AM +0200, Marco Felsch wrote:
>> Some phy's don't report the correct phy-id, e.g. the TJA1102 dual-port
>> report 0 for the 2nd port. To fix this a driver needs to supply the
>> phyid instead and tell the phy framework to not try to readout the
>> phyid. The latter case is done via the new 'phy_id_broken' flag which
>> tells the phy framework to skip phyid readout for the corresponding phy.
> 
> In general, we try to avoid work around for broken hardware in the
> core. Please try to solve this within nxp-tja11xx.c.

Agreed, and one way to solve working around broken PHY identification 
registers is to provide them through the compatible string via 
"ethernet-phyAAAA.BBBB". This forces the PHY library not to read from 
those registers yet instantiate the PHY device and force it to bind to a 
certain phy_driver.
-- 
Florian