linux-kernel - Re: [PATCH net 1/1] net: dsa: qca: ar9331: reorder MDIO write sequence

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Message-ID: <3bdbe4e2-00c9-afee-5bda-7267ff2bda3e@gmail.com>
Date:   Tue, 3 Aug 2021 02:49:23 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Oleksij Rempel <o.rempel@...gutronix.de>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Russell King <linux@...linux.org.uk>
Cc:     Pengutronix Kernel Team <kernel@...gutronix.de>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mips@...r.kernel.org
Subject: Re: [PATCH net 1/1] net: dsa: qca: ar9331: reorder MDIO write
 sequence



On 8/2/2021 11:37 PM, Oleksij Rempel wrote:
> In case of this switch we work with 32bit registers on top of 16bit
> bus. Some registers (for example access to forwarding database) have
> trigger bit on the first 16bit half of request and the result +
> configuration of request in the second half. Without this patch, we would
> trigger database operation and overwrite result in one run.
> 
> To make it work properly, we should do the second part of transfer
> before the first one is done.
> 
> So far, this rule seems to work for all registers on this switch.
> 
> Fixes: ec6698c272de ("net: dsa: add support for Atheros AR9331 built-in switch")
> Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
> Reviewed-by: Andrew Lunn <andrew@...n.ch>

Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
-- 
Florian