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Subject: Re: [PATCH v1] clocksource: Sigma Designs Tango 27 MHz xtal
To: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>,
        Thomas Gleixner <tglx@linutronix.de>
References: <5613E45C.5020208@sigmadesigns.com> <5614549F.2070002@linaro.org>
 <5614D66A.1060402@sigmadesigns.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Mans Rullgard <mans@mansr.com>,
        Mason <slash.tmp@free.fr>
From: Daniel Lezcano <daniel.lezcano@linaro.org>
Message-ID: <5614EA23.5080503@linaro.org>
Date: Wed, 7 Oct 2015 11:47:15 +0200
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On 10/07/2015 10:23 AM, Marc Gonzalez wrote:

[ ... ]

>>> +++ b/drivers/clocksource/tango_xtal.c
>>> @@ -0,0 +1,46 @@
>>> +#include <linux/clocksource.h>
>>> +#include <linux/sched_clock.h>
>>> +#include <linux/of_address.h>
>>> +#include <linux/delay.h>
>>> +#include <linux/clk.h>
>>
>> #include <linux/init.h> is missing.
>
> For my education: this header is already indirectly included;
> The directive should be explicit to prevent breakage in case
> other (implicit) includes are reorganized?

Yes, exactly.

The 'clocksource.h' header includes 'init.h' only for the 
'clocksource_default_clock' function. If this function disappears, or 
the __init section is removed, then the 'init.h' inclusion won't make 
sense anymore in the header file. By removing it, that will break all 
code relying on the implicit inclusion.

So the rule of thumb I apply to myself is always to explicitly include 
the headers in the C file even if it is already implicitly included. 
This rule is valid only if the header file is not using intensively code 
coming from the implicit inclusion like static inlines etc ...

>>> +static void __iomem *xtal_in_cnt;
>>> +static struct delay_timer delay_timer;
>>> +
>>> +static unsigned long read_xtal_counter(void)
>>> +{
>>> +	return readl_relaxed(xtal_in_cnt);
>>> +}
>>> +
>>> +static u64 read_sched_clock(void)
>>> +{
>>> +	return read_xtal_counter();
>>> +}
>>
>> static u64 *notrace* read_sched_clock(void)
>
> What about read_clocksource? and read_xtal_counter?

See commit 89e6a13b88.

   -- Daniel


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