Changelog ========= v2: Fixed feedback on usage of HWMON interfaces in patch 2. Fan === Currently /sys/bus/acpi/devices/TOS6208:00/fan allows controlling the fan by writing 0 (off) or 1 (on at low speed). However when reading I have observed values up to 64 (fan at full speed during prime95 stress test). Removing the check for "zero or one" shows that on the Z830 at least 64 levels do indeed seem possible. In fact higher values can be written. But anything above ~50 seems to max out the RPM. I don't know how to detect the supported range, so I have not created a patch for this. Advice is welcome. Fan RPM ======= There is a way to read Fan RPM: #define HCI_FAN_RPM 0x45 This one is weird. On windows I have observed the cooling self test program (which supposedly verifies that the cooling is working correctly) calling this a few different ways. Here is a summary of what I managed to figure out: HCI_SET, 0x45, 0, 1, 0, 0: This sets the fan to run at max speed, but it will not be visible when reading /sys/bus/acpi/devices/TOS6208:00/fan. I will refer to this operation as "set-max-fan" below. The only way I found to stop it running at max RPM is to use HCI_FAN (e.g. 0 > /sys/bus/acpi/devices/TOS6208:00/fan or call the ACPI method directly). However the get method is more interesting: HCI_GET, 0x45, 0, 1, 0, 0 returns: {0x0, 0x45, fan_rpm, 0x1db0, 0x0, 0x0} I believe fan_rpm is accurate, without any scaling factors needed: * It behaves properly (higher value when fan is louder/faster/higher pitched, 0 when fan is off). * It matches the value range reported by HwInfo64 on Windows (which seems to be able to read this, I have not looked into how it does that). * Unfortunately there is no tool by Toshiba that exposes the numerical value that I can find (that would have been ideal). Nor is it shown in BIOS. The Windows tools "Toshiba PC Health Monitor" reports everything in percentages. Yes even the temperatures! * It is definitely a loud and whiny fan, even by laptop standards, so the high reported RPM range of 3540-7600 RPM could make sense. Though it did seem a bit high. * Finally, to be sure, I borrowed a tachometer from work. Yes, the fan really spins that fast. Byt it is only 30 mm, so I guess that makes sense. HCI_GET 0x45, 0, 0, 0, 0 returns: {0x0, 0x45, fan_rpm, 0x0, 0x0, 0x0} The Windows software does *not* use this variant as far as I have observed. It appears to work the same except that it doesn't return 0x1db0 in index 3. I'm not sure, but I strongly suspect 0x1db0 could be the max RPM (7600). The most I have observed when using "set-max-fan" is 0x1da6 (7590 RPM), which is very close. Note that this is significantly more than I can get using just HCI_FAN, which seems to max out at 0x17ac (6060 RPM). Patches ======= I'm not personally particularly interested in user space control of fan speed, plus the fact that there is a way to make the fan go faster than the *other* max speed makes me wonder about the safety of running the fan at that speed for prolonged periods of time. Thus, I have only added a read-only hwmon interface for reading the fan RPM. I elected to use the same call that the Windows code does, which fetches what I believe is the max RPM. I think it is safer to stay as close as possible to that code. However I don't currently make use of this value, suggestions for where to use it are welcome. Note! I assume that if the FAN RPM call do not result in an error, that it is in fact supported. This may not be true. I would welcome testing by anyone who owns a Toshiba laptop! Arvid Norlander (2): platform/x86: toshiba_acpi: Add fan RPM reading (internals) platform/x86: toshiba_acpi: Add fan RPM reading (hwmon interface) drivers/platform/x86/Kconfig | 1 + drivers/platform/x86/toshiba_acpi.c | 102 ++++++++++++++++++++++++++++ 2 files changed, 103 insertions(+) base-commit: b90cb1053190353cc30f0fef0ef1f378ccc063c5 -- 2.37.3