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

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Date:   Wed, 1 Aug 2018 15:10:31 -0700
From:   Arun Parameswaran <arun.parameswaran@...adcom.com>
To:     Andrew Lunn <andrew@...n.ch>
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

Hi Andrew,

On 18-08-01 02:55 PM, Andrew Lunn wrote:
>> md->core_clk = devm_clk_get(&pdev->dev, NULL);
>> if (md->core_clk == ERR_PTR(-ENOENT) || md->core_clk == ERR_PTR(-EINVAL)) {
>> 	/* clock is optional, without it the default
>> 	 * rate divider register values will be used
>> 	 */
>> 	md->core_clk = NULL;
>> } else if (IS_ERR(md->core_clk)) {
>> 	return PTR_ERR(md->core_clk);
>> } else {
>> 	rc = clk_prepare_enable(md->core_clk);
>> 	...
>> }
> 
> 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.

In the other places where I used the clock, the return values were being
ignored.

The 'else' part should have been, I apologize for the confusion.

if (md->core_clk == ERR_PTR(-ENOENT) || md->core_clk == ERR_PTR(-EINVAL)) {
 	/* clock is optional, without it the default
 	 * rate divider register values will be used
 	 */
 	md->core_clk = NULL;
} else if (IS_ERR(md->core_clk)) {
 	return PTR_ERR(md->core_clk);
} else {
	rc = clk_prepare_enable(md->core_clk);
	if (rc) {
		dev_err(&pdev->dev, "failed to enable core clk\n");
		return rc;
	}
}


Thanks
Arun