linux-kernel - Re: [PATCH] Input: ff-core - Correct magnitude setting for rumble compatibility

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]

Message-ID: <Ya8L5x7cL5GKmL0y@google.com>
Date:   Mon, 6 Dec 2021 23:23:19 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Charles Keepax <ckeepax@...nsource.cirrus.com>
Cc:     linux-input@...r.kernel.org, patches@...nsource.cirrus.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Input: ff-core - Correct magnitude setting for rumble
 compatibility

On Tue, Nov 30, 2021 at 01:50:39PM +0000, Charles Keepax wrote:
> When converting a rumble into a periodic effect, for compatibility,
> the magnitude is effectively calculated using:
> 
> magnitude = max(strong_rubble / 3 + weak_rubble / 6, 0x7fff);
> 
> The rumble magnitudes are both u16 and the resulting magnitude is
> s16. The max is presumably an attempt to limit the result of the
> calculation to the maximum possible magnitude for the s16 result,
> and thus should be a min.
> 
> However in the case of strong = weak = 0xffff, the result of the first
> part of the calculation is 0x7fff, meaning that the min would be
> redundant anyway, so simply remove the current max.
> 
> Signed-off-by: Charles Keepax <ckeepax@...nsource.cirrus.com>

Applied, thank you.

-- 
Dmitry