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Commit 053819e0 authored by Shilpasri G Bhat's avatar Shilpasri G Bhat Committed by Rafael J. Wysocki
Browse files

cpufreq: powernv: Handle throttling due to Pmax capping at chip level 



The On-Chip-Controller(OCC) can throttle cpu frequency by reducing the
max allowed frequency for that chip if the chip exceeds its power or
temperature limits. As Pmax capping is a chip level condition report
this throttling behavior at chip level and also do not set the global
'throttled' on Pmax capping instead set the per-chip throttled
variable. Report unthrottling if Pmax is restored after throttling.

This patch adds a structure to store chip id and throttled state of
the chip.

Signed-off-by: default avatarShilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: default avatarPreeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent a34e63b1

drivers/cpufreq/powernv-cpufreq.c

+55 −4
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#include <linux/smp.h>

#include <linux/of.h>

#include <linux/reboot.h>

#include <linux/slab.h>



#include <asm/cputhreads.h>

#include <asm/firmware.h>
@@ -42,6 +43,13 @@ 
static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];

static bool rebooting, throttled;



static struct chip {

	unsigned int id;

	bool throttled;

} *chips;



static int nr_chips;



/*

 * Note: The set of pstates consists of contiguous integers, the

 * smallest of which is indicated by powernv_pstate_info.min, the
@@ -301,22 +309,33 @@ static inline unsigned int get_nominal_index(void) 
static void powernv_cpufreq_throttle_check(unsigned int cpu)

{

	unsigned long pmsr;

	int pmsr_pmax, pmsr_lp;

	int pmsr_pmax, pmsr_lp, i;



	pmsr = get_pmspr(SPRN_PMSR);



	for (i = 0; i < nr_chips; i++)

		if (chips[i].id == cpu_to_chip_id(cpu))

			break;



	/* Check for Pmax Capping */

	pmsr_pmax = (s8)PMSR_MAX(pmsr);

	if (pmsr_pmax != powernv_pstate_info.max) {

		throttled = true;

		pr_info("CPU %d Pmax is reduced to %d\n", cpu, pmsr_pmax);

		pr_info("Max allowed Pstate is capped\n");

		if (chips[i].throttled)

			goto next;

		chips[i].throttled = true;

		pr_info("CPU %d on Chip %u has Pmax reduced to %d\n", cpu,

			chips[i].id, pmsr_pmax);

	} else if (chips[i].throttled) {

		chips[i].throttled = false;

		pr_info("CPU %d on Chip %u has Pmax restored to %d\n", cpu,

			chips[i].id, pmsr_pmax);

	}



	/*

	 * Check for Psafe by reading LocalPstate

	 * or check if Psafe_mode_active is set in PMSR.

	 */

next:

	pmsr_lp = (s8)PMSR_LP(pmsr);

	if ((pmsr_lp < powernv_pstate_info.min) ||

				(pmsr & PMSR_PSAFE_ENABLE)) {
@@ -414,6 +433,33 @@ static struct cpufreq_driver powernv_cpufreq_driver = { 
	.attr		= powernv_cpu_freq_attr,

};



static int init_chip_info(void)

{

	unsigned int chip[256];

	unsigned int cpu, i;

	unsigned int prev_chip_id = UINT_MAX;



	for_each_possible_cpu(cpu) {

		unsigned int id = cpu_to_chip_id(cpu);



		if (prev_chip_id != id) {

			prev_chip_id = id;

			chip[nr_chips++] = id;

		}

	}



	chips = kmalloc_array(nr_chips, sizeof(struct chip), GFP_KERNEL);

	if (!chips)

		return -ENOMEM;



	for (i = 0; i < nr_chips; i++) {

		chips[i].id = chip[i];

		chips[i].throttled = false;

	}



	return 0;

}



static int __init powernv_cpufreq_init(void)

{

	int rc = 0;
@@ -429,6 +475,11 @@ static int __init powernv_cpufreq_init(void) 
		return rc;

	}



	/* Populate chip info */

	rc = init_chip_info();

	if (rc)

		return rc;



	register_reboot_notifier(&powernv_cpufreq_reboot_nb);

	return cpufreq_register_driver(&powernv_cpufreq_driver);

}