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Commit eaa7571b authored by Henrique de Moraes Holschuh's avatar Henrique de Moraes Holschuh Committed by Len Brown
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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: default avatarHenrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent fe98a52c

drivers/misc/thinkpad_acpi.c

+12 −4
Original line number Diff line number Diff line
@@ -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;