netdev - Re: [RFC PATCH net-next v2 02/17] net: mdio: ipq8064: switch to write/readl function

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Message-ID: <YJAHj/IWZLEZeDmL@Ansuel-xps.localdomain>
Date:   Mon, 3 May 2021 16:24:15 +0200
From:   Ansuel Smith <ansuelsmth@...il.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH net-next v2 02/17] net: mdio: ipq8064: switch to
 write/readl function

On Mon, May 03, 2021 at 02:49:34PM +0200, Andrew Lunn wrote:
> On Mon, May 03, 2021 at 01:06:54AM +0200, Ansuel Smith wrote:
> > Use readl/writel function instead of regmap function to make sure no
> > value is cached and align to other similar mdio driver.
> 
> regmap is O.K. to use, so long as you tell it not to cache. Look at
> how to use volatile in regmap.
> 
> You might be able to follow what lan9303_mdio.c is doing.
> 
>     Andrew

Was thinking more about the overhead of using regmap instead of plain
writel. Or is it minimal?