From 5e3119e15fed5b9a9a7e528665ff098a4a8dbdbc Mon Sep 17 00:00:00 2001 From: Finn Thain Date: Sat, 5 Sep 2020 09:02:20 +1000 Subject: [PATCH] powerpc/tau: Check processor type before enabling TAU interrupt 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: 1da177e4c3f41 ("Linux-2.6.12-rc2") Signed-off-by: Finn Thain Tested-by: Stan Johnson Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/c281611544768e758bd58fe812cf702a5bd2d042.1599260540.git.fthain@telegraphics.com.au --- arch/powerpc/kernel/tau_6xx.c | 33 ++++++++++++++------------------- arch/powerpc/platforms/Kconfig | 5 ++--- 2 files changed, 16 insertions(+), 22 deletions(-) diff --git a/arch/powerpc/kernel/tau_6xx.c b/arch/powerpc/kernel/tau_6xx.c index b8d7e7d..614b5b2 100644 --- a/arch/powerpc/kernel/tau_6xx.c +++ b/arch/powerpc/kernel/tau_6xx.c @@ -40,6 +40,8 @@ static struct tau_temp unsigned char grew; } tau[NR_CPUS]; +static bool tau_int_enable; + #undef DEBUG /* 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) { -#ifdef CONFIG_TAU_INT - /* - * 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); + u32 maybe_tie = tau_int_enable ? THRM1_TIE : 0; - /* setup THRM2, - * threshold, valid bit, enable interrupts, interrupt when above threshold - */ - mtspr (SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V | THRM1_TIE); -#else - /* 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 + /* setup THRM1, threshold, valid bit, interrupt when below threshold */ + mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | maybe_tie | THRM1_TID); + + /* setup THRM2, threshold, valid bit, interrupt when above threshold */ + mtspr(SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V | maybe_tie); } static void TAUupdate(int cpu) @@ -142,9 +135,8 @@ static void tau_timeout(void * info) local_irq_save(flags); cpu = smp_processor_id(); -#ifndef CONFIG_TAU_INT - TAUupdate(cpu); -#endif + if (!tau_int_enable) + TAUupdate(cpu); size = tau[cpu].high - tau[cpu].low; if (size > min_window && ! tau[cpu].grew) { @@ -225,6 +217,9 @@ static int __init TAU_init(void) 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); if (!tau_workq) return -ENOMEM; @@ -234,7 +229,7 @@ static int __init TAU_init(void) queue_work(tau_workq, &tau_work); 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; return 0; diff --git a/arch/powerpc/platforms/Kconfig b/arch/powerpc/platforms/Kconfig index fb7515b..9fe36f0 100644 --- a/arch/powerpc/platforms/Kconfig +++ b/arch/powerpc/platforms/Kconfig @@ -223,9 +223,8 @@ config TAU temperature within 2-4 degrees Celsius. This option shows the current on-die temperature in /proc/cpuinfo if the cpu supports it. - Unfortunately, on some chip revisions, this sensor is very inaccurate - and in many cases, does not work at all, so don't assume the cpu - temp is actually what /proc/cpuinfo says it is. + Unfortunately, this sensor is very inaccurate when uncalibrated, so + don't assume the cpu temp is actually what /proc/cpuinfo says it is. config TAU_INT bool "Interrupt driven TAU driver (DANGEROUS)" -- 2.7.4