linux-kernel - Re: [PATCH] iio: sx9310: Fix semtech,avg-pos-strength setting when

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:   Fri, 20 Nov 2020 10:21:04 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     Doug Anderson <dianders@...omium.org>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-iio <linux-iio@...r.kernel.org>,
        Daniel Campello <campello@...omium.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Gwendal Grignou <gwendal@...omium.org>,
        Evan Green <evgreen@...omium.org>
Subject: Re: [PATCH] iio: sx9310: Fix semtech,avg-pos-strength setting when > 16

Quoting Doug Anderson (2020-11-20 10:16:28)
> 
> Checking the math for the documented possible values of pos.  What we want:
> 
> 0 => 0
> 16 => 1
> 64 => 2
> 128 => 3
> 256 => 4
> 512 => 5
> 1024 => 6
> 4294967295 => 7
> 
> So looks OK.  Do we care about anything other than the documented
> numbers?  If my understanding of ilog2 is correct, then you'll get the
> wrong answer for 17.  I think you could fix it with:
> 
> pos = min(max(ilog2(pos), 3), 11) - (pos >= 32 ? 4 : 3);
> 

I don't think we really care about the rounding but to be consistent
with the first two it is better to do that. I'll send a fix.