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From: Thomas Gleixner <tglx@linutronix.de>
To: Felix Fietkau <nbd@nbd.name>
Cc: linux-kernel@vger.kernel.org, daniel.lezcano@linaro.org,
	paul.burton@imgtec.com
Subject: Re: [PATCH] clocksource: mips-gic-timer: fix clocksource counter width
Date: Wed, 28 Feb 2018 10:27:08 +0100 (CET)	[thread overview]
Message-ID: <alpine.DEB.2.21.1802281025390.1886@nanos.tec.linutronix.de> (raw)
In-Reply-To: <207b6722-a506-1e6a-c81c-a530e772dfa6@nbd.name>

On Wed, 28 Feb 2018, Felix Fietkau wrote:
> On 2018-02-28 09:56, Thomas Gleixner wrote:
> > On Wed, 21 Feb 2018, Felix Fietkau wrote:
> > 
> >> This code needs to use ffs instead of fls on the mask to determine the
> >> shift for reading the GIC_CONFIG_COUNTBITS field.
> > 
> > Why?
> >>  	count_width = read_gic_config() & GIC_CONFIG_COUNTBITS;
> >> -	count_width >>= __fls(GIC_CONFIG_COUNTBITS);
> >> +	count_width >>= __ffs(GIC_CONFIG_COUNTBITS);
> This code is trying to extract the GIC_CONFIG_COUNTBITS field from
> read_gic_config(), so it needs to shift count_width right by the index
> of the least significant bit (__ffs) instead of the most significant bit
> (__fls) of the field mask.

Sure, but that information wants to be in the changelog.

Thanks,

	tglx

      reply	other threads:[~2018-02-28  9:26 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-21 12:47 [PATCH] clocksource: mips-gic-timer: fix clocksource counter width Felix Fietkau
2018-02-28  8:56 ` Thomas Gleixner
2018-02-28  9:19   ` Felix Fietkau
2018-02-28  9:27     ` Thomas Gleixner [this message]

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