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 viresh.kumar@linaro.org ---
Gautham/Vaidy: I hope this fixes the problem we discussed for your patchset.
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 */ };