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ACPI: thinkpad-acpi: update fan firmware documentation

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Update some stuff in the in-code text describing the ThinkPad fan
firmware.  This patch has no code changes.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Henrique de Moraes Holschuh 2007-04-21 11:08:29 -03:00 committed by Len Brown
parent efa27145df
commit f51d1a3984
1 changed files with 13 additions and 15 deletions
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28
drivers/misc/thinkpad_acpi.c
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@ -1852,16 +1852,17 @@ static int volume_write(char *buf)
* ACPI GFAN method: returns fan level
*
* see TPACPI_FAN_WR_ACPI_SFAN
* EC 0x2f not available if GFAN exists
* EC 0x2f (HFSP) not available if GFAN exists
*
* TPACPI_FAN_WR_ACPI_SFAN:
* ACPI SFAN method: sets fan level, 0 (stop) to 7 (max)
*
* EC 0x2f might be available *for reading*, but never for writing.
* EC 0x2f (HFSP) might be available *for reading*, but do not use
* it for writing.
*
* TPACPI_FAN_WR_TPEC:
* ThinkPad EC register 0x2f (HFSP): fan control loop mode Supported
* on almost all ThinkPads
* ThinkPad EC register 0x2f (HFSP): fan control loop mode
* Supported on almost all ThinkPads
*
* Fan speed changes of any sort (including those caused by the
* disengaged mode) are usually done slowly by the firmware as the
@ -1875,12 +1876,13 @@ static int volume_write(char *buf)
* 7 automatic mode engaged;
* (default operation mode of the ThinkPad)
* fan level is ignored in this mode.
* 6 disengage mode (takes precedence over bit 7);
* 6 full speed mode (takes precedence over bit 7);
* not available on all thinkpads. May disable
* the tachometer, and speeds up fan to 100% duty-cycle,
* which speeds it up far above the standard RPM
* levels. It is not impossible that it could cause
* hardware damage.
* the tachometer while the fan controller ramps up
* the speed (which can take up to a few *minutes*).
* Speeds up fan to 100% duty-cycle, which is far above
* the standard RPM levels. It is not impossible that
* it could cause hardware damage.
* 5-3 unused in some models. Extra bits for fan level
* in others, but still useless as all values above
* 7 map to the same speed as level 7 in these models.
@ -1916,9 +1918,8 @@ static int volume_write(char *buf)
* FIRMWARE BUG: always read 0x84 first, otherwise incorrect readings
* might result.
*
* FIRMWARE BUG: when EC 0x2f bit 6 is set (disengaged mode), this
* register is not invalidated in ThinkPads that disable tachometer
* readings. Thus, the tachometer readings go stale.
* FIRMWARE BUG: may go stale while the EC is switching to full speed
* mode.
*
* For firmware bugs, refer to:
* http://thinkwiki.org/wiki/Embedded_Controller_Firmware#Firmware_Issues
@ -2283,9 +2284,6 @@ static int fan_read(char *p)
len += sprintf(p + len, "status:\t\t%s\n",
(status != 0) ? "enabled" : "disabled");
/* No ThinkPad boots on disengaged mode, we can safely
* assume the tachometer is online if fan control status
* was unknown */
if ((rc = fan_get_speed(&speed)) < 0)
return rc;