From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jacob Pan <jacob.jun.pan@linux.intel.com>
Subject: Re: [PATCH v2 2/2] powercap/rapl: reduce ipi calls
Date: Wed, 13 Jan 2016 09:51:24 -0800
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To: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>, LKML <linux-kernel@vger.kernel.org>, Linux PM <linux-pm@vger.kernel.org>, Rafael Wysocki <rafael.j.wysocki@intel.com>, "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>, X86 Kernel <x86@kernel.org>, Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>, Peter Zijlstra <peterz@infradead.org>, jacob.jun.pan@linux.intel.com

On Wed, 13 Jan 2016 17:36:10 +0100
Borislav Petkov <bp@alien8.de> wrote:

> On Wed, Jan 13, 2016 at 08:21:13AM -0800, Jacob Pan wrote:
> > Thanks for bring this out. I didn't mean to ignore. I thought my
> > point was stated in the commit message there was no point of going
> > back and forth. Read-Modify-Write is quite common, not just for
> > RAPL could be used by future code. Sorry if I wasn't clear.
> 
> But it also shows that it doesn't suffice for all your needs. So why
> add it?
> 
> You can much better define your own functions which do all the MSR
> handling you require and call them with smp_call_function_*.
> 
yeah, that is what I did in the original patch.
https://lkml.org/lkml/2015/12/7/1090

Then i was suggested to add a rmw msr api for the common good :), I
think it is a good idea since such operation is not limited to RAPL
driver. Other register access APIs such as regmap have more complete
selections.


Jacob