path: root/init
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authorHenrique de Moraes Holschuh <hmh@hmh.eng.br>2009-06-18 00:40:17 -0300
committerLen Brown <len.brown@intel.com>2009-06-18 01:30:57 -0400
commitd73772474f6ebbacbe820c31c0fa1cffa7160246 (patch)
tree7564212618d43910de01a818c0cdef5759ad12a9 /init
parentd7880f10c5d42ba182a97c1fd41d41d0b8837097 (diff)
thinkpad-acpi: support the second fan on the X61
Support reading the tachometer of the auxiliary fan of a X60/X61. It was found out by sheer luck, that bit 0 of EC register 0x31 (formely HBRV) selects which fan is active for tachometer readings through EC 0x84/0x085: 0 for fan1, 1 for fan2. Many thanks to Christoph Kl??nter, to Whoopie, and to weasel, who helped confirm that behaviour. Fan control through EC HFSP applies to both fans equally, regardless of the state of bit 0 of EC 0x31. That matches the way the DSDT uses HFSP. In order to better support the secondary fan, export a second tachometer over hwmon, and add defensive measures to make sure we are reading the correct tachometer. Support for the second fan is whitelist-based, as I have not found anything obvious to look for in the DSDT to detect the presence of the second fan. Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br> Signed-off-by: Len Brown <len.brown@intel.com>
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