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Commit f4e0bcf0 authored by Guenter Roeck's avatar Guenter Roeck Committed by Linus Torvalds
Browse files

hwmon: (coretemp) Add comments describing the handling of HT CPUs 



The coretemp driver provides a single set of device attributes for each
physical core of a HT CPU to avoid duplicate sensors.  This
functionality was introduced with commit d883b9f0 ("hwmon:
(coretemp) Skip duplicate CPU entries").

Commit e40cc4bd ("x86/hwmon: register alternate sibling upon CPU
removal") extends this functionality to register the HT sibling of a CPU
which is taken offline, to ensure that sensor attributes are provided if
at least one HT sibling of a core is online.

Add comments into the code describing the functionality in some more
detail.

Signed-off-by: default avatarGuenter Roeck <guenter.roeck@ericsson.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Durgadoss R <durgadoss.r@intel.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5f2e8e2b

drivers/hwmon/coretemp.c

+18 −2
Original line number Original line Diff line number Diff line
@@ -506,7 +506,13 @@ static int create_core_data(struct platform_data *pdata, 
	if (attr_no > MAX_CORE_DATA - 1)

	if (attr_no > MAX_CORE_DATA - 1)

		return -ERANGE;

		return -ERANGE;





	/* Skip if it is a HT core, Not an error */

	/*

	 * Provide a single set of attributes for all HT siblings of a core

	 * to avoid duplicate sensors (the processor ID and core ID of all

	 * HT siblings of a core is the same).

	 * Skip if a HT sibling of this core is already online.

	 * This is not an error.

	 */

	if (pdata->core_data[attr_no] != NULL)

	if (pdata->core_data[attr_no] != NULL)

		return 0;

		return 0;
@@ -763,10 +769,20 @@ static void __cpuinit put_core_offline(unsigned int cpu) 
	if (pdata->core_data[indx] && pdata->core_data[indx]->cpu == cpu)

	if (pdata->core_data[indx] && pdata->core_data[indx]->cpu == cpu)

		coretemp_remove_core(pdata, &pdev->dev, indx);

		coretemp_remove_core(pdata, &pdev->dev, indx);





	/* Online the HT version of this core, if any */

	/*

	 * If a core is taken offline, but a HT sibling of the same core is

	 * still online, register the alternate sibling. This ensures that

	 * exactly one set of attributes is provided as long as at least one

	 * HT sibling of a core is online.

	 */

	for_each_sibling(i, cpu) {

	for_each_sibling(i, cpu) {

		if (i != cpu) {

		if (i != cpu) {

			get_core_online(i);

			get_core_online(i);

			/*

			 * Display temperature sensor data for one HT sibling

			 * per core only, so abort the loop after one such

			 * sibling has been found.

			 */

			break;

			break;

		}

		}

	}

	}