hwmon: (coretemp) Extend the bitmask to read temperature to 0xff

BugLink: https://bugs.launchpad.net/bugs/2103427

The Intel Software Development manual defines the temperature digital
readout as the bits [22:16] of the IA32_[PACKAGE]_THERM_STATUS registers.
Bit 23 is specified as reserved.

In recent processors, however, the temperature digital readout uses bits
[23:16]. In those processors, using the bitmask 0x7f would lead to
incorrect readings if the temperature deviates from TjMax by more than
127 degrees Celsius.

Although not guaranteed, bit 23 is likely to be 0 in processors from a few
generations ago. The temperature reading would still be correct in those
processors when using a 0xff bitmask.

Model-specific provisions can be made for older processors in which bit 23
is not 0 should the need arise.

Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Link: https://lore.kernel.org/r/20240425171311.19519-4-ricardo.neri-calderon@linux.intel.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
(cherry picked from commit f0c344c000d09e38a0240b4a6ccbcd553b18e762)
Signed-off-by: Thibault Ferrante <thibault.ferrante@canonical.com>
Acked-by: Andrei Gherzan <andrei.gherzan@canonical.com>
Acked-by: Massimiliano Pellizzer <massimiliano.pellizzer@canonical.com>
Signed-off-by: Mehmet Basaran <mehmet.basaran@canonical.com>

This commit is contained in:

Ricardo Neri

2025-03-17 16:52:07 +01:00

committed by

Mehmet Basaran

parent f98fb0e2a8

commit 1a650c1e70

1 changed files with 1 additions and 1 deletions

									
										drivers/hwmon/coretemp.c
									
		+1
		-1
	
												View File
												
				@@ -411,7 +411,7 @@ static ssize_t show_temp(struct device *dev,

						 * Return it instead of reporting an error which doesn't

						 * really help at all.

						 */

						tdata->temp = tjmax - ((eax >> 16) & 0x7f) * 1000;

						tdata->temp = tjmax - ((eax >> 16) & 0xff) * 1000;

						tdata->last_updated = jiffies;

					}