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powerpc/tau: Check processor type before enabling TAU interrupt

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According to Freescale's documentation, MPC74XX processors have an
erratum that prevents the TAU interrupt from working, so don't try to
use it when running on those processors.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/c281611544768e758bd58fe812cf702a5bd2d042.1599260540.git.fthain@telegraphics.com.au
This commit is contained in:
Finn Thain
2020-09-05 09:02:20 +10:00
committed by Michael Ellerman
parent 420ab2bc75
commit 5e3119e15f
2 changed files with 16 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files

33
arch/powerpc/kernel/tau_6xx.c
View File

@@ -40,6 +40,8 @@ static struct tau_temp
unsigned char grew; unsigned char grew;
} tau[NR_CPUS]; } tau[NR_CPUS];
static bool tau_int_enable;
#undef DEBUG #undef DEBUG
/* TODO: put these in a /proc interface, with some sanity checks, and maybe /* TODO: put these in a /proc interface, with some sanity checks, and maybe
@@ -54,22 +56,13 @@ static struct tau_temp
static void set_thresholds(unsigned long cpu) static void set_thresholds(unsigned long cpu)
{ {
#ifdef CONFIG_TAU_INT u32 maybe_tie = tau_int_enable ? THRM1_TIE : 0;
/*
* setup THRM1,
* threshold, valid bit, enable interrupts, interrupt when below threshold
*/
mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | THRM1_TIE | THRM1_TID);
/* setup THRM2, /* setup THRM1, threshold, valid bit, interrupt when below threshold */
* threshold, valid bit, enable interrupts, interrupt when above threshold mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | maybe_tie | THRM1_TID);
*/
mtspr (SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V | THRM1_TIE); /* setup THRM2, threshold, valid bit, interrupt when above threshold */
#else mtspr(SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V | maybe_tie);
/* same thing but don't enable interrupts */
mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | THRM1_TID);
mtspr(SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V);
#endif
} }
static void TAUupdate(int cpu) static void TAUupdate(int cpu)
@@ -142,9 +135,8 @@ static void tau_timeout(void * info)
local_irq_save(flags); local_irq_save(flags);
cpu = smp_processor_id(); cpu = smp_processor_id();
#ifndef CONFIG_TAU_INT if (!tau_int_enable)
TAUupdate(cpu); TAUupdate(cpu);
#endif
size = tau[cpu].high - tau[cpu].low; size = tau[cpu].high - tau[cpu].low;
if (size > min_window && ! tau[cpu].grew) { if (size > min_window && ! tau[cpu].grew) {
@@ -225,6 +217,9 @@ static int __init TAU_init(void)
return 1; return 1;
} }
tau_int_enable = IS_ENABLED(CONFIG_TAU_INT) &&
!strcmp(cur_cpu_spec->platform, "ppc750");
tau_workq = alloc_workqueue("tau", WQ_UNBOUND, 1, 0); tau_workq = alloc_workqueue("tau", WQ_UNBOUND, 1, 0);
if (!tau_workq) if (!tau_workq)
return -ENOMEM; return -ENOMEM;
@@ -234,7 +229,7 @@ static int __init TAU_init(void)
queue_work(tau_workq, &tau_work); queue_work(tau_workq, &tau_work);
pr_info("Thermal assist unit using %s, shrink_timer: %d ms\n", pr_info("Thermal assist unit using %s, shrink_timer: %d ms\n",
IS_ENABLED(CONFIG_TAU_INT) ? "interrupts" : "workqueue", shrink_timer); tau_int_enable ? "interrupts" : "workqueue", shrink_timer);
tau_initialized = 1; tau_initialized = 1;
return 0; return 0;

5
arch/powerpc/platforms/Kconfig
View File

@@ -223,9 +223,8 @@ config TAU
temperature within 2-4 degrees Celsius. This option shows the current temperature within 2-4 degrees Celsius. This option shows the current
on-die temperature in /proc/cpuinfo if the cpu supports it. on-die temperature in /proc/cpuinfo if the cpu supports it.
Unfortunately, on some chip revisions, this sensor is very inaccurate Unfortunately, this sensor is very inaccurate when uncalibrated, so
and in many cases, does not work at all, so don't assume the cpu don't assume the cpu temp is actually what /proc/cpuinfo says it is.
temp is actually what /proc/cpuinfo says it is.
config TAU_INT config TAU_INT
bool "Interrupt driven TAU driver (DANGEROUS)" bool "Interrupt driven TAU driver (DANGEROUS)"