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Commit f51d1a39 authored by Henrique de Moraes Holschuh's avatar Henrique de Moraes Holschuh Committed by Len Brown
Browse files

ACPI: thinkpad-acpi: update fan firmware documentation 



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

Signed-off-by: default avatarHenrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent efa27145

drivers/misc/thinkpad_acpi.c

+13 −15
Original line number Diff line number Diff line
@@ -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;