netdev - Re: [PATCH v3 7/8] net: phy: Add support to configure clock in Broadcom iProc mdio mux

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Message-ID: <20180801221809.GH19257@lunn.ch>
Date:   Thu, 2 Aug 2018 00:18:09 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Arun Parameswaran <arun.parameswaran@...adcom.com>
Cc:     Russell King - ARM Linux <linux@...linux.org.uk>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Ray Jui <rjui@...adcom.com>,
        Scott Branden <sbranden@...adcom.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>, netdev@...r.kernel.org,
        bcm-kernel-feedback-list@...adcom.com,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v3 7/8] net: phy: Add support to configure clock in
 Broadcom iProc mdio mux

> > As Florian pointed out, the clk_ API is happy to take a NULL pointer
> > for a clock. So you don't need this last else.
> > 
> >     Andrew
> > 
> I do return with an error from the probe if the clk_prepare_enable() fails,
> so I was calling the prepare with a valid clock.

How many times do we need to say it?

NULL is a valid clock. 

int clk_prepare(struct clk *clk)
{
	if (!clk)
	   return 0;

	   return clk_core_prepare_lock(clk->core);
}

int clk_enable(struct clk *clk)
{
	if (!clk)
	   return 0;

	   return clk_core_enable_lock(clk->core);
}

clk_prepare_enable(NULL) returns 0, which is not an error.

	 Andrew