From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lukasz Majewski Subject: Re: [PATCH] cpufreq: set value of CPUFREQ_BOOST_FREQ to 0xABABABAB Date: Mon, 24 Mar 2014 09:21:12 +0100 Message-ID: <20140324092112.74f930d3@amdc2363> References: <78187ea173460c871eef31432ec2a80ec657fe30.1395643393.git.viresh.kumar@linaro.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-reply-to: <78187ea173460c871eef31432ec2a80ec657fe30.1395643393.git.viresh.kumar@linaro.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Viresh Kumar Cc: rjw@rjwysocki.net, linaro-kernel@lists.linaro.org, cpufreq@vger.kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, srivatsa.bhat@linux.vnet.ibm.com, ego@linux.vnet.ibm.com, svaidy@linux.vnet.ibm.com Hi Viresh, > Ideally, .driver_data field of struct cpufreq_frequency_table must > not be used by core at all. But during a recent change if its value > is same as CPUFREQ_BOOST_FREQ macro, then it is treated specially by > core. > > The value of this macro was set to ~2 earlier, i.e. 0xFFFFFFFD. In > case some driver is using this field for its own data and sets this > field to -3, then with two's complement that value will also become > 0xFFFFFFFD. > > To fix this issue, lets change value of this flag to a very uncommon > value which shouldn't be used by any driver unless they want to use > BOOST feature. > > Along with this update comments to make this more clear. > > Signed-off-by: Viresh Kumar > --- > > Gautham/Vaidy: I hope this fixes the problem we discussed for your > patchset. > I think that a name of the patchset, for which the current setting causes problem would be welcome here. Otherwise, I can only ask why it is not possible to add #define SPECIAL_SETTING ~3 ? > include/linux/cpufreq.h | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h > index c48e595..9f25d9d 100644 > --- a/include/linux/cpufreq.h > +++ b/include/linux/cpufreq.h > @@ -455,12 +455,18 @@ extern struct cpufreq_governor > cpufreq_gov_conservative; > * FREQUENCY TABLE HELPERS > * > *********************************************************************/ > +/* Special Values of .frequency field */ > #define CPUFREQ_ENTRY_INVALID ~0 > #define CPUFREQ_TABLE_END ~1 > -#define CPUFREQ_BOOST_FREQ ~2 > +/* Special Values of .driver_data field */ > +#define CPUFREQ_BOOST_FREQ 0xABABABAB > > struct cpufreq_frequency_table { > - unsigned int driver_data; /* driver specific data, > not used by core */ > + /* > + * driver specific data, not used by core unless it is set to > + * CPUFREQ_BOOST_FREQ. > + */ > + unsigned int driver_data; > unsigned int frequency; /* kHz - doesn't need to be > in ascending > * order */ > }; -- Best regards, Lukasz Majewski Samsung R&D Institute Poland (SRPOL) | Linux Platform Group