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From: Henrique de M. H. <hm...@hm...> - 2006-11-22 20:14:02
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From: Henrique de Moraes Holschuh <hm...@hm...> This patch documents the ThinkPad fan control strategies. Source of the data: 0. ibm-acpi source 1. DSDTs for various ThinkPads (770, X31, X40, X41, T43, A21m, T22) 2. http://thinkwiki.org/wiki/Embedded_Controller_Firmware#Firmware_Issues 3. http://thinkwiki.org/wiki/How_to_control_fan_speed 4. Various threads about windows fan control utilities in thinkpads.com Signed-off-by: Henrique de Moraes Holschuh <hm...@hm...> --- drivers/acpi/ibm_acpi.c | 110 +++++++++++++++++++++++++++++++++++++++++= +++++- 1 files changed, 108 insertions(+), 2 deletions(-) diff --git a/drivers/acpi/ibm_acpi.c b/drivers/acpi/ibm_acpi.c index 3a5f662..dadd55b 100644 --- a/drivers/acpi/ibm_acpi.c +++ b/drivers/acpi/ibm_acpi.c @@ -205,7 +205,7 @@ IBM_HANDLE(led, ec, "SLED", /* 570 */ IBM_HANDLE(beep, ec, "BEEP"); /* all except R30, R31 */ IBM_HANDLE(ecrd, ec, "ECRD"); /* 570 */ IBM_HANDLE(ecwr, ec, "ECWR"); /* 570 */ -IBM_HANDLE(fans, ec, "FANS"); /* X31, X40 */ +IBM_HANDLE(fans, ec, "FANS"); /* X31, X40, X41 */ =20 IBM_HANDLE(gfan, ec, "GFAN", /* 570 */ "\\FSPD", /* 600e/x, 770e, 770x */ @@ -231,6 +231,106 @@ struct ibm_thermal_sensors_struct { s32 temp[IBMACPI_MAX_THERMAL_SENSORS]; }; =20 +/* + * FAN ACCESS MODES + * + * IBMACPI_FAN_RD_ACPI_GFAN: + * ACPI GFAN method: returns fan level + * + * see IBMACPI_FAN_WR_ACPI_SFAN + * EC 0x2f not available if GFAN exists + * + * IBMACPI_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. + * + * IBMACPI_FAN_WR_TPEC: + * 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 + * maximum ammount of fan duty cycle change per second seems to be + * limited. + * + * Reading is not available if GFAN exists. + * Writing is not available if SFAN exists. + * + * Bits + * 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); + * 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. + * 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. + * 2-0 fan level (0..7 usually) + * 0x00 =3D stop + * 0x07 =3D max (set when temperatures critical) + * Some ThinkPads may have other levels, see + * IBMACPI_FAN_WR_ACPI_FANS (X31/X40/X41) + * + * FIRMWARE BUG: on some models, EC 0x2f might not be initialized at + * boot. Apparently the EC does not intialize it, so unless ACPI DSDT + * does so, its initial value is meaningless (0x07). + * + * For firmware bugs, refer to: + * http://thinkwiki.org/wiki/Embedded_Controller_Firmware#Firmware_Issue= s + * + * ---- + * + * ThinkPad EC register 0x84 (LSB), 0x85 (MSB): + * Main fan tachometer reading (in RPM) + * + * This register is present on all ThinkPads with a new-style EC, and + * it is known not to be present on the A21m/e, and T22, as there is + * something else in offset 0x84 according to the ACPI DSDT. Other + * ThinkPads from this same time period (and earlier) probably lack the + * tachometer as well. + * + * Unfortunately a lot of ThinkPads with new-style ECs but whose firwmar= e + * was never fixed by IBM to report the EC firmware version string + * probably support the tachometer (like the early X models), so + * detecting it is quite hard. We need more data to know for sure. + * + * 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. + * + * For firmware bugs, refer to: + * http://thinkwiki.org/wiki/Embedded_Controller_Firmware#Firmware_Issue= s + * + * IBMACPI_FAN_WR_ACPI_FANS: + * ThinkPad X31, X40, X41. Not available in the X60. + * + * FANS ACPI handle: takes three arguments: low speed, medium speed, + * high speed. ACPI DSDT seems to map these three speeds to levels + * as follows: STOP LOW LOW MED MED HIGH HIGH HIGH HIGH + * (this map is stored on FAN0..FAN8 as "0,1,1,2,2,3,3,3,3") + * + * The speeds are stored on handles + * (FANA:FAN9), (FANC:FANB), (FANE:FAND). + * + * There are three default speed sets, acessible as handles: + * FS1L,FS1M,FS1H; FS2L,FS2M,FS2H; FS3L,FS3M,FS3H + * + * ACPI DSDT switches which set is in use depending on various + * factors. + * + * IBMACPI_FAN_WR_TPEC is also available and should be used to + * command the fan. The X31/X40/X41 seems to have 8 fan levels, + * but the ACPI tables just mention level 7. + */ + enum fan_status_access_mode { IBMACPI_FAN_NONE =3D 0, /* No fan status or control */ IBMACPI_FAN_RD_ACPI_GFAN, /* Use ACPI GFAN */ @@ -1722,7 +1822,7 @@ static int fan_init(void) /* all other models implement TP EC 0x2f control */ =20 if (fans_handle) { - /* X31, X40 */ + /* X31, X40, X41 */ fan_control_access_mode =3D IBMACPI_FAN_WR_ACPI_FANS; fan_control_commands |=3D @@ -1742,6 +1842,9 @@ static int fan_get_status(u8 *status) { u8 s; =20 + /* TODO: + * Add IBMACPI_FAN_RD_ACPI_FANS ? */ + switch (fan_status_access_mode) { case IBMACPI_FAN_RD_ACPI_GFAN: /* 570, 600e/x, 770e, 770x */ @@ -1950,6 +2053,9 @@ static int fan_write_cmd_speed(const cha { int speed; =20 + /* TODO: + * Support speed <low> <medium> <high> ? */ + if (sscanf(cmd, "speed %d", &speed) !=3D 1) return 0; =20 |
