Embedded Controller Firmware
ThinkPad Embedded Controller Firmware
The ThinkPad has an embedded microcontroller (EC) which is responsible for many of the background tasks on a laptop. Embedded Controller Chips lists the different embedded microcontrollers found on various ThinkPads. This page concerns itself with the various embedded controller firmwares.
The more precise way to refer to a particular instace of the ThinkPad firmware is not the ThinkPad name (ThinkPad T43) or model number (2668-XXX), but rather by the firmware model string, which is unique to BIOS-and-firmware-image-compatible ThinkPads. E.g. there are both R52 and T43 ThinkPads with firmware model TP-70: they share the same BIOS and EC firmware, and also the same bugs... There is a list of the ThinkPad BIOS/EC types in the BIOS Upgrade Downloads page.
The firmware model string is "TP-" and the two first characters of the BIOS/EC version strings (e.g. BIOS 1YET29WW and EC 1YHT29WW are for the firmware model TP-1Y, which happens to be some of the T43, and the T43p).
Old-style ThinkPad EC firmware
Not much is known about the ECs on the older numeric-series ThinkPads, or the early A, X and T-series models. These microcontrollers don't seem to support field-upgradeable firmware, and only the BIOS SMAPI and DSDT ACPI interfaces are really available for driver writers.
- Interfaces:
- EC register map
- ACPI DSDT / APM
- SMAPI
- CMOS memory map
New-style ThinkPad EC firmware
Apparently, all newer ThinkPad ECs are a Renesas H8S/2161BV or another compatible H8S/300 microcontroller with very similar firmware.
- Interfaces:
- Forward-compatible EC register map
- ACPI DSDT, APM (deprecated in newer models)
- Renesas H8S LPC3A (?), LPC3B (HDAPS firmware, Battery information)
- ACPI SMAPI methods
- SMAPI
- CMOS memory map
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FIXME
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tpctl, tpb and other drivers, please someone expand on how well they work with the new ThinkPads
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Firmware issues
Various bugs have been observed in the ThinkPad EC firmware of various models. Most of them were fixed in later revisions, but a few are either very dangerous and driver writers need to always work around them, or have never been fixed. One must keep in mind that many of the bugs fixed by IBM or Lenovo could cause serious problems, but might never be noticed by driver developers, because they usually keep their ThinkPads up-to-date. People that don't keep their ThinkPad firmware up-to-date are excellent guinea pigs...
Bug: Advanced battery query causes EC hang
- Severity: critical
- Linux annoyance level: harmless
- Windows annoyance level: unknown
- Fix: available from IBM, but not for all affected models
- Information: thread in linux-thinkpad ML
- Models affected:
- TP-1R (T40, T40p, T41, T41p, T42, T42p): no fix available
- TP-1Y (T43 26xx, T43p): fixed by firmware 1YHT28WW (1.05) and newer
- TP-70 (T43 18xx, R52), TP-76 (R52), TP-78 (R51e): likely buggy, unknown status (might be fixed in latest firmwares)
- other ThinkPads featuring advanced battery queries: unknown status; every model supported by tp_smapi advanced battery information is a candidate for this bug
The EC LPC3B advanced battery query function 0x0B (only used by tp_smapi) has a hideous bug that causes the EC to misbehave and crash (usually hanging the entire ThinkPad). This function must never be called on a buggy firmware.
No Linux drivers use this function, as its purpose is currently unknown.
Bug: Fan control loop status is not initialized
- Severity: low
- Linux annoyance level: low
- Windows annoyance level: unknown
- Fix: unknown status at this time, usually worked around by ACPI DSDT.
- Information: thinkpads.com fan control programs forum, linux-thinkpad ML thread 1, linux-thinkpad ML thread 2
- Models affected (no ACPI workaround):
- Models NOT affected (confirmed by reports):
- R60 TP-7C, T60/p TP-79, T23 TP-1A, A31 TP-1G, R51 TP-1V, T40/p,T41/p,T42/p,R50/p,R51 TP-1R
- Models that are probably affected (need reports):
- Models that are probably not affected (some reports would be nice):
- T3x, X3x, T42, anything newer than the T43, R52.
The EC does not correctly initializes its 0x2f (fan control) register, so ibm-acpi cannot determine the correct status of the fan control until something writes to the fan control register for the first time.
Many models do write to the fan control register in their ACPI DSDT methods, which provides a work-around. This usually fixes the issue during suspend and wakeup.
So far, there are only reports of wrong readings of 0x07, no other wrong value has been observed. Note that 0x07 might be a correct value if the system is in emergency fan mode (level 7).
Bug: Fan control loop pulses the fan in an annoying pattern
- Severity: low
- Linux annoyance level: critical
- Windows annoyance level: critical
- Fix: available from IBM, but incorrectly fixed on some models. Unofficial fix available for firmware hackers.
- Workaround: A software workaround is available using an ACPI fan control script, but this overrides the embedded controller's fan control algorithm.
- Information: thinkpads.com forum thread, thinkpads.com forum thread, Problem with fan noise
- Models affected:
The fan control loop will vary the fan speed quite a lot, in a very annoying pattern. The broken fix on the T43 firmware causes very loud and annoying pulses every 30s.
People have reportedly returned ThinkPads because of this bug.
Bug: Tachometer registers not invalidated in disengaged mode
- Severity: low
- Linux annoyance level: minor
- Windows annoyance level: minor
- Fix: none available
- Models affected:
- Unknown (disengaged mode might not be supported on all ThinkPads)
When the fan control loop is placed in disengaged mode (bit 6 of EC register 0x2f is set) where no tachometer readings take place, the EC does not set the tachometer registers (0x84, 0x85) to 0xFF to signal an invalid reading. Instead, the registers are simply not updated anymore and retain the last tachometer reading that took place.
This bug can be easily worked around in drivers.
