linux-kernel - Re: [PATCH 1/4] pwm: mxs: implement ->apply

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

Message-ID: <20190923091745.ehvz4zi2riyanmug@pengutronix.de>
Date:   Mon, 23 Sep 2019 11:17:45 +0200
From:   Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>,
        Russell King <linux@...linux.org.uk>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        devicetree@...r.kernel.org, linux-pwm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org
Subject: Re: [PATCH 1/4] pwm: mxs: implement ->apply

Hello,

[expanded the recipents to include RMK and the clk list]

On Mon, Sep 23, 2019 at 11:04:39AM +0200, Rasmus Villemoes wrote:
> On 23/09/2019 10.24, Uwe Kleine-König wrote:
> > Also there is a bug already in .config: You are not supposed to call
> > clk_get_rate if the clk might be off.
> 
> Interesting, I didn't know that. So the prepare_enable logic needs to be
> moved before we start computing the period/duty cycles. Do you know why
> it has apparently worked so far? I would have thought such a rule would
> be enforced by the clock framework, or at least produced a warning.

FTR: This is documented in the kerneldoc code comment to clk_get_rate in
include/linux/clk.h.

Assuming this is relevant, it might indeed make sense to add a
WARN_ONCE for this.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |