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@xxxxxxxxxx>
---
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 */
};
--
1.7.12.rc2.18.g61b472e
--
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