netdev - Re: [PATCH net] net: dsa: microchip: disable EEE for KSZ8567/KSZ9567/KSZ9896/KSZ9897.

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Message-ID: <20240808110216.20a1787c@wsk>
Date: Thu, 8 Aug 2024 11:02:16 +0200
From: Lukasz Majewski <lukma@...x.de>
To: Martin Whitaker <foss@...tin-whitaker.me.uk>
Cc: netdev@...r.kernel.org, UNGLinuxDriver@...rochip.com,
 Woojung.Huh@...rochip.com, o.rempel@...gutronix.de,
 Arun.Ramadoss@...rochip.com, kuba@...nel.org
Subject: Re: [PATCH net] net: dsa: microchip: disable EEE for
 KSZ8567/KSZ9567/KSZ9896/KSZ9897.

Hi Martin,

> As noted in the device errata [1-8], EEE support is not fully
> operational in the KSZ8567, KSZ9477, KSZ9567, KSZ9896, and KSZ9897
> devices, causing link drops when connected to another device that
> supports EEE. The patch series "net: add EEE support for KSZ9477
> switch family" merged in commit 9b0bf4f77162 caused EEE support to be
> enabled in these devices. A fix for this regression for the KSZ9477
> alone was merged in commit 08c6d8bae48c2. This patch extends this fix
> to the other affected devices.
> 
> [1]
> https://ww1.microchip.com/downloads/aemDocuments/documents/UNG/ProductDocuments/Errata/KSZ8567R-Errata-DS80000752.pdf
> [2]
> https://ww1.microchip.com/downloads/aemDocuments/documents/UNG/ProductDocuments/Errata/KSZ8567S-Errata-DS80000753.pdf
> [3]
> https://ww1.microchip.com/downloads/aemDocuments/documents/UNG/ProductDocuments/Errata/KSZ9477S-Errata-DS80000754.pdf
> [4]
> https://ww1.microchip.com/downloads/aemDocuments/documents/UNG/ProductDocuments/Errata/KSZ9567R-Errata-DS80000755.pdf
> [5]
> https://ww1.microchip.com/downloads/aemDocuments/documents/UNG/ProductDocuments/Errata/KSZ9567S-Errata-DS80000756.pdf
> [6]
> https://ww1.microchip.com/downloads/aemDocuments/documents/UNG/ProductDocuments/Errata/KSZ9896C-Errata-DS80000757.pdf
> [7]
> https://ww1.microchip.com/downloads/aemDocuments/documents/UNG/ProductDocuments/Errata/KSZ9897R-Errata-DS80000758.pdf
> [8]
> https://ww1.microchip.com/downloads/aemDocuments/documents/UNG/ProductDocuments/Errata/KSZ9897S-Errata-DS80000759.pdf
> 
> Fixes: 69d3b36ca045 ("net: dsa: microchip: enable EEE support") # for
> KSZ8567/KSZ9567/KSZ9896/KSZ9897 Link:
> https://lore.kernel.org/netdev/137ce1ee-0b68-4c96-a717-c8164b514eec@martin-whitaker.me.uk/
> Signed-off-by: Martin Whitaker <foss@...tin-whitaker.me.uk> ---
>  drivers/net/dsa/microchip/ksz_common.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/net/dsa/microchip/ksz_common.c
> b/drivers/net/dsa/microchip/ksz_common.c index
> b074b4bb0629..cebc6eaa932b 100644 ---
> a/drivers/net/dsa/microchip/ksz_common.c +++
> b/drivers/net/dsa/microchip/ksz_common.c @@ -2578,7 +2578,11 @@
> static u32 ksz_get_phy_flags(struct dsa_switch *ds, int port) if
> (!port) return MICREL_KSZ8_P1_ERRATA;
>  		break;
> +	case KSZ8567_CHIP_ID:
>  	case KSZ9477_CHIP_ID:
> +	case KSZ9567_CHIP_ID:
> +	case KSZ9896_CHIP_ID:
> +	case KSZ9897_CHIP_ID:
>  		/* KSZ9477 Errata DS80000754C
>  		 *
>  		 * Module 4: Energy Efficient Ethernet (EEE) feature
> select must @@ -2588,6 +2592,13 @@ static u32
> ksz_get_phy_flags(struct dsa_switch *ds, int port)
>  		 *   controls. If not disabled, the PHY ports can
> auto-negotiate
>  		 *   to enable EEE, and this feature can cause link
> drops when
>  		 *   linked to another device supporting EEE.
> +		 *
> +		 * The same item appears in the errata for the
> KSZ9567, KSZ9896,
> +		 * and KSZ9897.
> +		 *
> +		 * A similar item appears in the errata for the
> KSZ8567, but
> +		 * provides an alternative workaround. For now, use
> the simple
> +		 * workaround of disabling the EEE feature for this
> device too. */
>  		return MICREL_NO_EEE;
>  	}
> --
> 2.41.1

Reviewed-by: Lukasz Majewski <lukma@...x.de>


Best regards,

Lukasz Majewski

--

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