linux-kernel - RE: [PATCH] clk: Add functions to get optional clocks

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: <OSBPR01MB1766E6AFE37986B2E2B5E35DF5530@OSBPR01MB1766.jpnprd01.prod.outlook.com>
Date:   Wed, 18 Jul 2018 13:56:26 +0000
From:   Phil Edworthy <phil.edworthy@...esas.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Russell King <linux@...linux.org.uk>
CC:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Simon Horman <horms@...ge.net.au>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-clk <linux-clk@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH] clk: Add functions to get optional clocks

Hi Russell,

On 18 July 2018 14:19, Geert Uytterhoeven wrote:
> On Wed, Jul 18, 2018 at 3:02 PM Russell King - ARM Linux  wrote:
> > On Wed, Jul 18, 2018 at 01:57:38PM +0100, Phil Edworthy wrote:
> > > Behaves the same as (devm_)clk_get except where there is no clock
> > > producer. In this case, instead of returning -ENOENT, the function
> > > returns NULL. This makes error checking simpler and allows
> > > clk_prepare_enable, etc to be called on the returned reference
> > > without additional checks.
> >
> > How does this work with non-DT systems, where looking a clock up which
> > isn't yet registered with clkdev returns -ENOENT ?
> >
> > (clkdev doesn't know when all clocks are registered with it.)
> 
> Good question.
> 
> I guess all drivers trying to handle optional clocks this way are already broken
> on non-DT systems where clocks may be registered late...

So how do non-DT systems that look a clock up which isn't yet
registered with clkdev, determine that an optional clock is there
or not?

Thanks
Phil