Author: Henrique de Moraes Holschuh <[EMAIL PROTECTED]>
AuthorDate: Sat Apr 21 11:08:29 2007 -0300
Committer: Len Brown <[EMAIL PROTECTED]>
CommitDate: Sat Apr 21 23:30:33 2007 -0400
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: Henrique de Moraes Holschuh <[EMAIL PROTECTED]>
Signed-off-by: Len Brown <[EMAIL PROTECTED]>
drivers/misc/thinkpad_acpi.c | 28 +++++++++++++---------------
1 files changed, 13 insertions(+), 15 deletions(-)
diff --git a/drivers/misc/thinkpad_acpi.c b/drivers/misc/thinkpad_acpi.c
index 1683bfe..4131a78 100644
@@ -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
* 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.
- * 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:
@@ -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)
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