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ACPI: thinkpad-acpi: add a safety net for TPEC fan control mode 

The Linux ThinkPad community is not positive that all ThinkPads that do
HFSP EC fan control do implement full-speed and auto modes, some of the
earlier ones supporting HFSP might not.

If the EC ignores the AUTO or FULL-SPEED bits, it will pay attention to the
lower three bits that set the fan level.  And as thinkpad-acpi was leaving
these set to zero, it would stop(!) the fan, which is Not A Good Thing.

So, as a safety net, we now make sure to also set the fan level part of the
HFSP register to speed 7 for full-speed, and a minimum of speed 4 for auto
mode.

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 2007-04-24 11:48:18 -03:00 committed by Len Brown
parent fe98a52ce7
commit eaa7571b2d
1 changed files with 12 additions and 4 deletions
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16
drivers/misc/thinkpad_acpi.c
View File

@ -3185,6 +3185,13 @@ static int fan_set_level(int level)
((level < 0) || (level > 7)))
return -EINVAL;
/* safety net should the EC not support AUTO
* or FULLSPEED mode bits and just ignore them */
if (level & TP_EC_FAN_FULLSPEED)
level |= 7; /* safety min speed 7 */
else if (level & TP_EC_FAN_FULLSPEED)
level |= 4; /* safety min speed 4 */
if (!acpi_ec_write(fan_status_offset, level))
return -EIO;
else
@ -3233,8 +3240,10 @@ static int fan_set_enable(void)
break;
/* Don't go out of emergency fan mode */
if (s != 7)
s = TP_EC_FAN_AUTO;
if (s != 7) {
s &= 0x07;
s |= TP_EC_FAN_AUTO | 4; /* min fan speed 4 */
}
if (!acpi_ec_write(fan_status_offset, s))
rc = -EIO;
@ -3252,8 +3261,7 @@ static int fan_set_enable(void)
s &= 0x07;
/* Set fan to at least level 4 */
if (s < 4)
s = 4;
s |= 4;
if (!acpi_evalf(sfan_handle, NULL, NULL, "vd", s))
rc= -EIO;