linux-kernel - Re: [PATCH] clocksource/drivers/time-armada-370-xp: Fix the clock reference

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Date:	Wed, 10 Aug 2016 15:05:06 +0200
From:	Gregory CLEMENT <gregory.clement@...e-electrons.com>
To:	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
Cc:	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, Andrew Lunn <andrew@...n.ch>,
	Romain Perier <romain.perier@...e-electrons.com>,
	Jason Cooper <jason@...edaemon.net>,
	Boris BREZILLON <boris.brezillon@...e-electrons.com>,
	Stefan Roese <stefan.roese@...il.com>,
	Ezequiel Garcia <ezequiel.garcia@...e-electrons.com>,
	Sebastian Careba <nitroshift@...oo.com>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	linux-arm-kernel@...ts.infradead.org,
	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
Subject: Re: [PATCH] clocksource/drivers/time-armada-370-xp: Fix the clock reference

Hi Thomas,
 
 On mer., août 10 2016, Thomas Petazzoni <thomas.petazzoni@...e-electrons.com> wrote:

> Hello,
>
> On Wed, 10 Aug 2016 10:09:08 +0200, Gregory CLEMENT wrote:
>> While converting the init function to return an error, the wrong clock
>> was get. This lead to wrong clock rate and slow down the kernel. For
>> example, before the patch a typical boot was around 15s after it was 1
>> minute slower.
>> 
>> Fixes: 12549e27c63c ("clocksource/drivers/time-armada-370-xp: Convert init function to return error")
>> 
>> Signed-off-by: Gregory CLEMENT <gregory.clement@...e-electrons.com>
>> ---
>>  drivers/clocksource/time-armada-370-xp.c | 1 -
>>  1 file changed, 1 deletion(-)
>> 
>> diff --git a/drivers/clocksource/time-armada-370-xp.c b/drivers/clocksource/time-armada-370-xp.c
>> index 719b478d136e..3c39e6f45971 100644
>> --- a/drivers/clocksource/time-armada-370-xp.c
>> +++ b/drivers/clocksource/time-armada-370-xp.c
>> @@ -338,7 +338,6 @@ static int __init armada_xp_timer_init(struct device_node *np)
>>  	struct clk *clk = of_clk_get_by_name(np, "fixed");
>>  	int ret;
>>  
>> -	clk = of_clk_get(np, 0);
>
> I think to avoid this mistake, we should rewrite the code as:
>
> 	struct *clk;
> 	int ret;
>
> 	clk = of_clk_get_by_name(np, "fixed");
> 	if (IS_ERR(clk)) {
> 		...
> 	
>

OK I can do it. it will be alos more coherent with the other _init
function.

Gregory

> Indeed, I find confusing a block that starts with error checking, and
> it's probably what lead to this of_clk_get() being added here.
>
> Thomas
> -- 
> Thomas Petazzoni, CTO, Free Electrons
> Embedded Linux and Kernel engineering
> http://free-electrons.com

-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com