linux-kernel - Re: [PATCH 2/2] PM / OPP: check for existing OPP list when initialising from device tree

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 for Android: free password hash cracker in your pocket

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

Date:	Wed, 1 May 2013 11:51:36 -0500
From:	Nishanth Menon <nm@...com>
To:	Sudeep KarkadaNagesha <Sudeep.KarkadaNagesha@....com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
	Rob Landley <rob@...dley.net>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Shawn Guo <shawn.guo@...aro.org>,
	"devicetree-discuss@...ts.ozlabs.org" 
	<devicetree-discuss@...ts.ozlabs.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>
Subject: Re: [PATCH 2/2] PM / OPP: check for existing OPP list when
 initialising from device tree

On 17:33-20130501, Sudeep KarkadaNagesha wrote:
> On 01/05/13 16:04, Nishanth Menon wrote:
> > On 12:11-20130501, Sudeep.KarkadaNagesha@....com wrote:
> >> From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@....com>
[...]
> >> diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
> >> index 4dfdc01..66d52d2 100644
> >> --- a/drivers/base/power/opp.c
> >> +++ b/drivers/base/power/opp.c
> >> @@ -706,6 +706,11 @@ static int of_init_opp_table_from_ofnode(struct device *dev,
> >>  	const __be32 *val;
> >>  	int nr;
> >>  
> >> +	/* Check for existing list for 'dev' */
> >> +	dev_opp = find_device_opp(dev);
> >> +	if (!IS_ERR(dev_opp))
> >> +		return 0; /* Device OPP already initialized */
> >> +
> > It gets a little touchy here -> the normal expectation is for the OPP
> > entries to be populated onetime at boot.
> > For example - driver bug where same device was attempted twice Vs the
> > usecase you mention here - how'd we differentiate between the two?
> 
> Do we really need to differentiate ? How about returning -EEXIST ?
We have tried to provide enough debug information for developers to
detect and fix their mistakes, error value is one part of the story for
callers, error messages emphasis on top of it for the developer.. But,
for some reason I might be led to believe probe and hotplug are separate
usecases - probe of a device indicates it's presence, and hotplug of a
device should ideally be a power state.. But that is just me.
-- 
Regards,
Nishanth Menon
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/