CoreSight

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2751 discussions

[PATCH v3] coresight: ete: Always save state on power down

by James Clark

System register ETMs and ETE are unlikely to be preserved on CPU power down. The ETE DT binding also never documented "arm,coresight-loses-context-with-cpu" so nobody would have legitimately been able to use that binding to fix it and ACPI has no such binding at all. Fix it by hard coding the setting for sysreg ETMs (ETE is always sysreg) or ACPI boots. Use a local variable when setting up save_state so that it's immune to concurrent probing when devices have different configurations which is an issue with modifying the global. This fixes the following error when using Coresight with ACPI on the FVP which supports CPU PM: coresight ete0: External agent took claim tag WARNING: drivers/hwtracing/coresight/coresight-core.c:248 at coresight_disclaim_device_unlocked+0xe0/0xe8, CPU#0: perf/117 Fixes: 35e1c9163e02 ("coresight: ete: Add support for ETE tracing") Signed-off-by: James Clark <james.clark(a)linaro.org> --- Fix PM save on ETE, which is an issue that showed up on the FVP when booted with ACPI and the newly enabled idle states. --- Changes in v3: - Setup using a local variable and then check drvdata->save_state at runtime so it's immune to concurrent probing with different configs. - Link to v2: https://lore.kernel.org/r/20260505-james-cs-ete-pm_save_enable-v2-1-d39c1f1… Changes in v2: - Expand rule to also save for ACPI and sysreg ETMs. Now module param is only read for MMIO ETMs and DT. - Drop change to save the result in drvdata as the single global is simpler. - Link to v1: https://lore.kernel.org/r/20260428-james-cs-ete-pm_save_enable-v1-0-c7a90ca… --- drivers/hwtracing/coresight/coresight-etm4x-core.c | 48 +++++++++++++++------- 1 file changed, 34 insertions(+), 14 deletions(-) diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index d565a73f0042..591dfe0bc635 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -56,10 +56,14 @@ MODULE_PARM_DESC(boot_enable, "Enable tracing on boot"); #define PARAM_PM_SAVE_NEVER 1 /* never save any state */ #define PARAM_PM_SAVE_SELF_HOSTED 2 /* save self-hosted state only */ +/* + * Save option for ETM4. ETE, sysreg ETM4s and ACPI boots ignore this option and + * will always save. + */ static int pm_save_enable = PARAM_PM_SAVE_FIRMWARE; module_param(pm_save_enable, int, 0444); MODULE_PARM_DESC(pm_save_enable, - "Save/restore state on power down: 1 = never, 2 = self-hosted"); + "Save/restore state on power down: 1 = never, 2 = self-hosted. MMIO and DT only."); static struct etmv4_drvdata *etmdrvdata[NR_CPUS]; static void etm4_set_default_config(struct etmv4_config *config); @@ -2012,7 +2016,7 @@ static int etm4_cpu_save(struct etmv4_drvdata *drvdata) { int ret = 0; - if (pm_save_enable != PARAM_PM_SAVE_SELF_HOSTED) + if (!drvdata->save_state) return 0; /* @@ -2127,7 +2131,7 @@ static void __etm4_cpu_restore(struct etmv4_drvdata *drvdata) static void etm4_cpu_restore(struct etmv4_drvdata *drvdata) { - if (pm_save_enable != PARAM_PM_SAVE_SELF_HOSTED) + if (!drvdata->save_state) return; if (coresight_get_mode(drvdata->csdev)) @@ -2212,6 +2216,17 @@ static void etm4_pm_clear(void) } } +static bool etm4x_always_pm_save(struct device *dev, struct csdev_access *csa) +{ + /* + * Only IO mem ETM devices will benefit from skipping PM save and only + * DT has the option to control it, not ACPI. Otherwise system register + * based ETMs and ETEs will always lose context on CPU power down, so + * always save. + */ + return !csa->io_mem || is_acpi_device_node(dev_fwnode(dev)); +} + static int etm4_add_coresight_dev(struct etm4_init_arg *init_arg) { int ret; @@ -2221,6 +2236,7 @@ static int etm4_add_coresight_dev(struct etm4_init_arg *init_arg) struct coresight_desc desc = { 0 }; u8 major, minor; char *type_name; + bool pm_save; if (!drvdata) return -EINVAL; @@ -2248,6 +2264,21 @@ static int etm4_add_coresight_dev(struct etm4_init_arg *init_arg) etm4_set_default(&drvdata->config); + if (etm4x_always_pm_save(dev, init_arg->csa)) + pm_save = true; + else if (pm_save_enable == PARAM_PM_SAVE_FIRMWARE) + pm_save = coresight_loses_context_with_cpu(dev); + else + pm_save = pm_save_enable != PARAM_PM_SAVE_NEVER; + + if (pm_save) { + drvdata->save_state = devm_kmalloc(dev, + sizeof(struct etmv4_save_state), + GFP_KERNEL); + if (!drvdata->save_state) + return -ENOMEM; + } + pdata = coresight_get_platform_data(dev); if (IS_ERR(pdata)) return PTR_ERR(pdata); @@ -2305,17 +2336,6 @@ static int etm4_probe(struct device *dev) if (ret) return ret; - if (pm_save_enable == PARAM_PM_SAVE_FIRMWARE) - pm_save_enable = coresight_loses_context_with_cpu(dev) ? - PARAM_PM_SAVE_SELF_HOSTED : PARAM_PM_SAVE_NEVER; - - if (pm_save_enable != PARAM_PM_SAVE_NEVER) { - drvdata->save_state = devm_kmalloc(dev, - sizeof(struct etmv4_save_state), GFP_KERNEL); - if (!drvdata->save_state) - return -ENOMEM; - } - raw_spin_lock_init(&drvdata->spinlock); drvdata->cpu = coresight_get_cpu(dev); --- base-commit: 971f3474f8898ae8bbab19a9b547819a5e6fbcf1 change-id: 20260420-james-cs-ete-pm_save_enable-4e994e35cdac Best regards, -- James Clark <james.clark(a)linaro.org>

2 weeks, 4 days

[PATCH] coresight: tmc: Fix overflow when calculating is bigger than 2GiB

by Leo Yan

When specifying a 2GB AUX buffer, the ETR driver ends up allocating only a 1MB buffer instead: # echo 'file coresight-tmc-etr.c +p' > \ /sys/kernel/debug/dynamic_debug/control # perf record -e cs_etm/@tmc_etr0,timestamp=0/u -C 0 -m ,2G -- test coresight tmc_etr0: allocated buffer of size 1024KB in mode 0 The page index is an 'int' type, and shifting it by PAGE_SHIFT overflows when the resulting value exceeds 2GB. This produces a negative value, causing the driver to fall back to the minimum buffer size (1MB). Cast the page index to a wider type to accommodate large buffer sizes. Also fix a similar issue in the buffer offset calculation. Reported-by: Michiel van Tol <michiel.vantol(a)arm.com> Fixes: 99443ea19e8b ("coresight: Add generic TMC sg table framework") Fixes: eebe8dbd8630 ("coresight: tmc: Decouple the perf buffer allocation from sysfs mode") Signed-off-by: Leo Yan <leo.yan(a)arm.com> --- drivers/hwtracing/coresight/coresight-tmc-etr.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c index cee82e52c4ea96b035f1db71b2d9a006bfc1c51e..990bbb721e1d712d7b93f1e36087fdaf9d3baa3b 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c @@ -154,7 +154,7 @@ tmc_pages_get_offset(struct tmc_pages *tmc_pages, dma_addr_t addr) for (i = 0; i < tmc_pages->nr_pages; i++) { page_start = tmc_pages->daddrs[i]; if (addr >= page_start && addr < (page_start + PAGE_SIZE)) - return i * PAGE_SIZE + (addr - page_start); + return (long)i * PAGE_SIZE + (addr - page_start); } return -EINVAL; @@ -1381,7 +1381,7 @@ alloc_etr_buf(struct tmc_drvdata *drvdata, struct perf_event *event, node = (event->cpu == -1) ? NUMA_NO_NODE : cpu_to_node(event->cpu); /* Use the minimum limit if the required size is smaller */ - size = nr_pages << PAGE_SHIFT; + size = (ssize_t)nr_pages << PAGE_SHIFT; size = max_t(ssize_t, size, TMC_ETR_PERF_MIN_BUF_SIZE); /* --- base-commit: eebe8dbd8630f51cf70b1f68a440cd3d7f7a914d change-id: 20260217-arm_coresight_fix_big_buffer_size-a8a41298369d Best regards, -- Leo Yan <leo.yan(a)arm.com>

2 weeks, 4 days

[PATCH v11 00/27] CoreSight: Refactor power management for CoreSight path

by Leo Yan

This series focuses on CoreSight path power management. The changes can be divided into four parts for review: Patches 01 - 09: Preparison for CPU PM: Fix helper enable failure handling. Refactor CPU ID stored in csdev. Move CPU lock to sysfs layer. Move per-CPU source pointer from etm-perf to core layer. Refactor etm-perf to retrieve source via per-CPU's event data for lockless and get source reference during AUX setup. Patches 10 - 12: Refactor CPU idle flow managed in the CoreSight core layer. Patches 13 - 22: Refactor path enable / disable with range, control path during CPU idle. Patches 23 - 24: Support the sink (TRBE) control during CPU idle. Patches 25 - 27: Move CPU hotplug into the core layer, and fix sysfs mode for hotplug. This series is rebased on the coresight-next branch and has been verified on Juno-r2 (ETM + ETR) and FVP RevC (ETE + TRBE). Built successfully for armv7 (ARCH=arm). --- Changes in v11: - Moved per-CPU source pointer from etm-perf to core (Suzuki). - Added grabbing/ungrabbing csdev for device reference (Suzuki). - Minor refine for error handling and logs in CPU PM (James). - Refactored etm-perf with fetching path/source from event data (Suzuki). - Fixed Helper error handling (sashiko). - Added Jie's test tag (thanks!). - Minor improvement for comments and commit logs. - Link to v10: https://lore.kernel.org/r/20260405-arm_coresight_path_power_management_impr… Changes in v10: - Removed redundant checks in ETMv4 PM callbacks (sashiko). - Added a new const structure etm4_cs_pm_ops (sashiko). - Used fine-grained spinlock on sysfs_active_config (sashiko). - Blocked notification after failures in save / restore to avoid lockups. - Changed Change CPUHP_AP_ARM_CORESIGHT_STARTING to CPUHP_AP_ARM_CORESIGHT_ONLINE so that the CPU hotplug callback runs in the thread context (sashiko). - Link to v9: https://lore.kernel.org/r/20260401-arm_coresight_path_power_management_impr… Changes in v9: - Changed to use per-CPU path pointer with lockless access. - Removed the change for adding csdev->path, the related refactoring will be sent separately. - Re-orged patches to avoid intermediate breakage (sashiko). - Link to v8: https://lore.kernel.org/r/20260325-arm_coresight_path_power_management_impr… Changes in v8: - Moved the "cpu" field in coresight_device for better pack with new patch 01 (Suzuki). - Added check if not set CPU for per_cpu_source/per_cpu_sink (Suzuki). - Renamed spinlock name in syscfg (Suzuki). - Refactored paired enable and disable path with new patches 10 and 12 (Suzuki). - Link to v7: https://lore.kernel.org/r/20260320-arm_coresight_path_power_management_impr… Signed-off-by: Leo Yan <leo.yan(a)arm.com> --- Leo Yan (26): coresight: Handle helper enable failure properly coresight: Extract device init into coresight_init_device() coresight: Populate CPU ID into coresight_device coresight: Remove .cpu_id() callback from source ops coresight: Take hotplug lock in enable_source_store() for Sysfs mode coresight: perf: Retrieve path and source from event data coresight: Take a reference on csdev coresight: Move per-CPU source pointer to core layer coresight: Grab per-CPU source device during AUX setup coresight: Register CPU PM notifier in core layer coresight: etm4x: Hook CPU PM callbacks coresight: etm4x: Remove redundant checks in PM save and restore coresight: syscfg: Use IRQ-safe spinlock to protect active variables coresight: Move source helper disabling to coresight_disable_path() coresight: Control path with range coresight: Use helpers to fetch first and last nodes coresight: Introduce coresight_enable_source() helper coresight: Save active path for system tracers coresight: etm4x: Set active path on target CPU coresight: etm3x: Set active path on target CPU coresight: sysfs: Use source's path pointer for path control coresight: Control path during CPU idle coresight: Add PM callbacks for sink device coresight: sysfs: Increment refcount only for system tracers coresight: Move CPU hotplug callbacks to core layer coresight: sysfs: Validate CPU online status for per-CPU sources Yabin Cui (1): coresight: trbe: Save and restore state across CPU low power state drivers/hwtracing/coresight/coresight-catu.c | 2 +- drivers/hwtracing/coresight/coresight-core.c | 530 ++++++++++++++++++--- drivers/hwtracing/coresight/coresight-cti-core.c | 9 +- drivers/hwtracing/coresight/coresight-etm-perf.c | 268 ++++++----- drivers/hwtracing/coresight/coresight-etm3x-core.c | 73 +-- drivers/hwtracing/coresight/coresight-etm4x-core.c | 166 ++----- drivers/hwtracing/coresight/coresight-priv.h | 6 + drivers/hwtracing/coresight/coresight-syscfg.c | 38 +- drivers/hwtracing/coresight/coresight-syscfg.h | 2 + drivers/hwtracing/coresight/coresight-sysfs.c | 133 ++---- drivers/hwtracing/coresight/coresight-trbe.c | 61 ++- include/linux/coresight.h | 15 +- include/linux/cpuhotplug.h | 2 +- 13 files changed, 833 insertions(+), 472 deletions(-) --- base-commit: 971f3474f8898ae8bbab19a9b547819a5e6fbcf1 change-id: 20251104-arm_coresight_path_power_management_improvement-dab4966f8280 Best regards, -- Leo Yan <leo.yan(a)arm.com>

3 weeks, 2 days

Re: [PATCH v11 00/27] CoreSight: Refactor power management for CoreSight path

by Leo Yan

On Wed, May 06, 2026 at 03:33:38PM +0800, Jie Gan wrote: [...] > Tested on QCOM sa8775p-ride platform with sysfs mode: Hi Jie, very appreciate for the testing! > === 1. Prerequisites === > PASS: Running as root > PASS: CoreSight bus present > PASS: Sink: tmc_etr0 > Sink is TRBE: 0 > PASS: Source: etm0 > Source CPU: 0 > Online CPUs: 8 > All CoreSight devices: > ctcu0 > cti_sys0 > etm0 > etm1 > etm2 > etm3 > etm4 > etm5 > etm6 > etm7 > funnel0 > funnel1 > funnel2 > funnel3 > funnel4 > funnel5 > funnel6 > funnel7 > replicator0 > replicator1 > replicator2 > stm0 > tmc_etf0 > tmc_etr0 > tmc_etr1 > tpdm0 > tpdm1 > tpdm10 > tpdm11 > tpdm2 > tpdm3 > tpdm4 > tpdm5 > tpdm6 > tpdm7 > tpdm8 > tpdm9 > > === 2. Sysfs mode: basic enable/disable === > PASS: Sink tmc_etr0 enabled > PASS: Source etm0 enabled > PASS: Source etm0 disabled cleanly > PASS: Sink tmc_etr0 disabled cleanly > > === 3. Sysfs mode: repeated enable/disable cycles (10x) === > PASS: 10 enable/disable cycles completed without error > > === 4. Sysfs: enable source with no active sink === > PASS: Enable without sink returned error (expected) > > === 5. Sysfs: enable/disable all online per-CPU sources === > etm0 (cpu0): enabled OK > etm1 (cpu1): enabled OK > etm2 (cpu2): enabled OK > etm3 (cpu3): enabled OK > etm4 (cpu4): enabled OK > etm5 (cpu5): enabled OK > etm6 (cpu6): enabled OK > etm7 (cpu7): enabled OK > PASS: All online per-CPU sources enabled/disabled successfully > > === 6. csdev->cpu sysfs attribute (Patch 3: CPU ID in coresight_device) === > etm0: cpu = 0 (OK) > etm1: cpu = 1 (OK) > etm2: cpu = 2 (OK) > etm3: cpu = 3 (OK) > etm4: cpu = 4 (OK) > etm5: cpu = 5 (OK) > etm6: cpu = 6 (OK) > etm7: cpu = 7 (OK) > PASS: All 8 per-CPU sources have valid 'cpu' attribute > > === 7. CPU online validation before path build (Patch 27) === > Offlining cpu1 (source: etm1) > [ 146.339051] psci: CPU1 killed (polled 0 ms) > PASS: P27: Enable on offline cpu1 rejected before path build > (enable_source=0) > [ 146.689573] Detected PIPT I-cache on CPU1 > [ 146.689635] GICv3: CPU1: found redistributor 100 region > 0:0x0000000017a80000 > [ 146.689801] CPU1: Booted secondary processor 0x0000000100 [0x410fd4b2] > cpu1 back online > > === 8. CPU hotplug: core layer disables full sysfs path on CPU offline > (Patch 26) === > Starting sysfs trace on cpu1 (source: etm1) > Offlining cpu1 while tracing active... > [ 147.498731] psci: CPU1 killed (polled 0 ms) > PASS: P26: Source auto-disabled by core coresight_dying_cpu() on CPU offline > Sink state after hotplug: 1 > PASS: No kernel errors in dmesg during hotplug > [ 148.365194] Detected PIPT I-cache on CPU1 > [ 148.365249] GICv3: CPU1: found redistributor 100 region > 0:0x0000000017a80000 > [ 148.365393] CPU1: Booted secondary processor 0x0000000100 [0x410fd4b2] > PASS: cpu1 re-onlined > > === 9. CPU hotplug: re-enable sysfs tracing after CPU re-online === > PASS: Tracing re-enabled on cpu1 after hotplug cycle > > === 10. CPU PM: path control during CPU idle (Patch 22) === > Sleeping 4s to allow CPU idle entry (source: etm0, cpu: 0)... > Idle entries on cpu0 during test: 49 > PASS: P22: Source still enabled after idle — path save/restore working > > Thanks, > Jie

3 weeks, 2 days

Re: [PATCH v6 04/13] coresight: etm4x: exclude ss_status from drvdata->config

by Leo Yan

On Wed, Apr 22, 2026 at 02:21:54PM +0100, Yeoreum Yun wrote: [...] > @@ -573,11 +573,9 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata) > etm4x_relaxed_write32(csa, config->res_ctrl[i], TRCRSCTLRn(i)); > > for (i = 0; i < caps->nr_ss_cmp; i++) { > - /* always clear status bit on restart if using single-shot */ > - if (config->ss_ctrl[i] || config->ss_pe_cmp[i]) > - config->ss_status[i] &= ~TRCSSCSRn_STATUS; > etm4x_relaxed_write32(csa, config->ss_ctrl[i], TRCSSCCRn(i)); > - etm4x_relaxed_write32(csa, config->ss_status[i], TRCSSCSRn(i)); > + /* always clear status and pending bits on restart if using single-shot */ > + etm4x_relaxed_write32(csa, 0x0, TRCSSCSRn(i)); I am not confident what is the right way to handle the pending bit. I looked a bit Arm ARM but still no clue. In particular, I suspect it may need to be handled when disabling the trace in etm4_disable_hw(). Let's make it clear with some internal check. > @@ -1829,8 +1829,8 @@ static ssize_t sshot_ctrl_store(struct device *dev, > raw_spin_lock(&drvdata->spinlock); > idx = config->ss_idx; > config->ss_ctrl[idx] = FIELD_PREP(TRCSSCCRn_SAC_ARC_RST_MASK, val); > - /* must clear bit 31 in related status register on programming */ > - config->ss_status[idx] &= ~TRCSSCSRn_STATUS; > + /* must clear bit 31 and 30 in related status register on programming */ > + drvdata->ss_status[idx] &= ~(TRCSSCSRn_STATUS | TRCSSCSRn_PENDING); Similarly, the question is: if it is in a pending state, how can we ensure the state machine works properly with the new settings? > raw_spin_unlock(&drvdata->spinlock); > return size; > } > @@ -1879,8 +1879,8 @@ static ssize_t sshot_pe_ctrl_store(struct device *dev, > raw_spin_lock(&drvdata->spinlock); > idx = config->ss_idx; > config->ss_pe_cmp[idx] = FIELD_PREP(TRCSSPCICRn_PC_MASK, val); > - /* must clear bit 31 in related status register on programming */ > - config->ss_status[idx] &= ~TRCSSCSRn_STATUS; > + /* must clear bit 31 and 30 in related status register on programming */ > + drvdata->ss_status[idx] &= ~(TRCSSCSRn_STATUS | TRCSSCSRn_PENDING); Ditto. Thanks, Leo

3 weeks, 2 days

Re: [PATCH] coresight: cti: Fix DT filter signals silently ignored

by Suzuki K Poulose

On Sun, 26 Apr 2026 17:59:34 +0800, Yingchao Deng wrote: > In cti_plat_process_filter_sigs(), after allocating a temporary > cti_trig_grp struct via kzalloc_obj(), the code never assigns tg->nr_sigs > = nr_filter_sigs. Since kzalloc zero-initialises the struct, tg->nr_sigs > remains 0. cti_plat_read_trig_group() guards with: > if (!tgrp->nr_sigs) > return 0; > > [...] Applied, thanks! [1/1] coresight: cti: Fix DT filter signals silently ignored https://git.kernel.org/coresight/c/551bb2fd5e4e Best regards, -- Suzuki K Poulose <suzuki.poulose(a)arm.com>

3 weeks, 2 days

Re: [PATCH v6 02/13] coresight: etm4x: fix underflow for nrseqstate

by Leo Yan

On Wed, Apr 22, 2026 at 02:21:52PM +0100, Yeoreum Yun wrote: > TCRSEQEVR<n> is implemented only when TCRIDR5.NUMSEQSTATE is 0b100, > in which case n ranges from 0 to 2; otherwise, TCRIDR5.NUMSEQSTATE is 0b000. > > Therefore, drvdata->nrseqstate should be checked before entering the loop. Since TRCSEQEVRn (n=0~2), to avoid confusion, we also need to rename ETM_MAX_SEQ_STATES to ETM_MAX_SEQ_TRANSITIONS and define it as 3: #define ETM_MAX_SEQ_TRANSITIONS 3 Then we don't allocate 4 items but use only 3 of them. Thanks, Leo

3 weeks, 2 days

[PATCH v2] coresight: ete: Always save state on power down

by James Clark

System register ETMs and ETE are unlikely to be preserved on CPU power down. The ETE DT binding also never documented "arm,coresight-loses-context-with-cpu" so nobody would have legitimately been able to use that binding to fix it and ACPI has no such binding at all. Fix it by hard coding the setting for sysreg ETMs (ETE is always sysreg) or ACPI boots. This fixes the following error when using Coresight with ACPI on the FVP which supports CPU PM: coresight ete0: External agent took claim tag WARNING: drivers/hwtracing/coresight/coresight-core.c:248 at coresight_disclaim_device_unlocked+0xe0/0xe8, CPU#0: perf/117 Fixes: 35e1c9163e02 ("coresight: ete: Add support for ETE tracing") Signed-off-by: James Clark <james.clark(a)linaro.org> --- Fix PM save on ETE, which is an issue that showed up on the FVP when booted with ACPI and the newly enabled idle states. --- Changes in v2: - Expand rule to also save for ACPI and sysreg ETMs. Now module param is only read for MMIO ETMs and DT. - Drop change to save the result in drvdata as the single global is simpler. - Link to v1: https://lore.kernel.org/r/20260428-james-cs-ete-pm_save_enable-v1-0-c7a90ca… --- drivers/hwtracing/coresight/coresight-etm4x-core.c | 42 +++++++++++++++------- 1 file changed, 30 insertions(+), 12 deletions(-) diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index d565a73f0042..b6b46c2f8ee8 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -56,10 +56,14 @@ MODULE_PARM_DESC(boot_enable, "Enable tracing on boot"); #define PARAM_PM_SAVE_NEVER 1 /* never save any state */ #define PARAM_PM_SAVE_SELF_HOSTED 2 /* save self-hosted state only */ +/* + * Save option for ETM4. ETE, sysreg ETM4s and ACPI boots ignore this option and + * will always save. + */ static int pm_save_enable = PARAM_PM_SAVE_FIRMWARE; module_param(pm_save_enable, int, 0444); MODULE_PARM_DESC(pm_save_enable, - "Save/restore state on power down: 1 = never, 2 = self-hosted"); + "Save/restore state on power down: 1 = never, 2 = self-hosted. MMIO and DT only."); static struct etmv4_drvdata *etmdrvdata[NR_CPUS]; static void etm4_set_default_config(struct etmv4_config *config); @@ -2212,6 +2216,17 @@ static void etm4_pm_clear(void) } } +static bool etm4x_always_pm_save(struct device *dev, struct csdev_access *csa) +{ + /* + * Only IO mem ETM devices will benefit from skipping PM save and only + * DT has the option to control it, not ACPI. Otherwise system register + * based ETMs and ETEs will always lose context on CPU power down, so + * always save. + */ + return !csa->io_mem || is_acpi_device_node(dev_fwnode(dev)); +} + static int etm4_add_coresight_dev(struct etm4_init_arg *init_arg) { int ret; @@ -2248,6 +2263,20 @@ static int etm4_add_coresight_dev(struct etm4_init_arg *init_arg) etm4_set_default(&drvdata->config); + if (etm4x_always_pm_save(dev, init_arg->csa)) + pm_save_enable = PARAM_PM_SAVE_SELF_HOSTED; + else if (pm_save_enable == PARAM_PM_SAVE_FIRMWARE) + pm_save_enable = coresight_loses_context_with_cpu(dev) ? + PARAM_PM_SAVE_SELF_HOSTED : PARAM_PM_SAVE_NEVER; + + if (pm_save_enable != PARAM_PM_SAVE_NEVER) { + drvdata->save_state = devm_kmalloc(dev, + sizeof(struct etmv4_save_state), + GFP_KERNEL); + if (!drvdata->save_state) + return -ENOMEM; + } + pdata = coresight_get_platform_data(dev); if (IS_ERR(pdata)) return PTR_ERR(pdata); @@ -2305,17 +2334,6 @@ static int etm4_probe(struct device *dev) if (ret) return ret; - if (pm_save_enable == PARAM_PM_SAVE_FIRMWARE) - pm_save_enable = coresight_loses_context_with_cpu(dev) ? - PARAM_PM_SAVE_SELF_HOSTED : PARAM_PM_SAVE_NEVER; - - if (pm_save_enable != PARAM_PM_SAVE_NEVER) { - drvdata->save_state = devm_kmalloc(dev, - sizeof(struct etmv4_save_state), GFP_KERNEL); - if (!drvdata->save_state) - return -ENOMEM; - } - raw_spin_lock_init(&drvdata->spinlock); drvdata->cpu = coresight_get_cpu(dev); --- base-commit: 971f3474f8898ae8bbab19a9b547819a5e6fbcf1 change-id: 20260420-james-cs-ete-pm_save_enable-4e994e35cdac Best regards, -- James Clark <james.clark(a)linaro.org>

3 weeks, 2 days

[PATCH 0/2] coresight: ete: Always save state on power down

by James Clark

Fix PM save on ETE, which is an issue that showed up on the FVP when booted with ACPI and the newly enabled idle states. Then refactor to clarify and avoid any probe order issues. Signed-off-by: James Clark <james.clark(a)linaro.org> --- James Clark (2): coresight: ete: Always save state on power down coresight: etm4x: Refactor pm_save_enable handling drivers/hwtracing/coresight/coresight-etm4x-core.c | 55 ++++++++++++++++------ drivers/hwtracing/coresight/coresight-etm4x.h | 1 + 2 files changed, 42 insertions(+), 14 deletions(-) --- base-commit: 971f3474f8898ae8bbab19a9b547819a5e6fbcf1 change-id: 20260420-james-cs-ete-pm_save_enable-4e994e35cdac Best regards, -- James Clark <james.clark(a)linaro.org>

3 weeks, 6 days

Re: [PATCH v6 00/13] fix several inconsistencies with sysfs configuration in etmX

by Leo Yan

On Fri, May 01, 2026 at 01:55:46PM +0100, Yeoreum Yun wrote: > Gentle ping in case of forgotten. This is on my todo list - let me finish the task in hand and then I will play a bit this series. Thanks, Leo

4 weeks

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