macbook21: Add CST entries

Hardware / Coreboot - Axel Holewa [posteo.de] - 10 January 2015 01:45 UTC

Due to the CST entries the machine uses less power running GNU/Linux-libre. This can be seen by monitoring CPU temperature and time left the machine can run on battery. CPU temperature measurements have been done with lm_sensors, battery querying with acpi. Tests have been done before applying this patch and after. In both cases the battery was fully loaded and the machine powered up on battery, without AC. In both tests the machine was idleing for more than 1 hour.

Without this patch battery was predicted to last 01:52:30 hours, CPU temperature first measurement showed 38 degrees. After 15 min idle, temperature has reached its maximum value in this test of 61 and 62 degrees (Core 0 and 1). Fan speed begins to increase shortly after 15 min. From its minimal value 1800 rpm it reaches 3100 rpm after 40 min. CPU temperature did not increase any further. After 60 min idle, the battery was predicted to still last 57 min.

With this patch battery was predicted to last 02:22:40 hours. That is plus 30 min. CPU temperature begins at 35 degrees. After 15 min temperature has reached 45 degrees; after 30 min it has reached the maximal temperature during this test of about 50 degrees. That is 10 degrees improvement. The fan stayed at minimal speed. After 60 min idle, the battery was predicted to still last 01:22:48 hours; a 25 minute improvement.

Change-Id: I6b2173df1dc09300329b61b51b79f4b9f4a8fb13

1682b8d macbook21: Add CST entries
src/mainboard/apple/macbook21/mainboard.c | 36 ++++++++++++++++++++++++++++-
1 file changed, 35 insertions(+), 1 deletion(-)

Upstream: review.coreboot.org

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