Re: [PATCH] clocksource: mips-gic-timer: fix clocksource counter width

From: Thomas Gleixner
Date: Wed Feb 28 2018 - 04:26:59 EST


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