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@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,
ETE registers are always system registers so it's highly unlikely there will be an implementation that preserves them on CPU power down. Also the ETE DT binding never documented "arm,coresight-loses-context-with-cpu" so nobody would have legitimately been able to use that binding to fix it.
Fix it by hard coding the setting for ETE and add a warning if the user tried to use the module parameter. Don't add a warning if loses-context-with-cpu is present in the DT as it's not a documented binding anyway. etm4_init_pm_save() needs to happen after drvdata is initialised so etm4x_is_ete() can be called.
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@linaro.org --- drivers/hwtracing/coresight/coresight-etm4x-core.c | 41 +++++++++++++++------- 1 file changed, 29 insertions(+), 12 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index d565a73f0042..a7fb680dd383 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -56,10 +56,11 @@ 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 ignores this option and always saves */ 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. ETM4 only.");
static struct etmv4_drvdata *etmdrvdata[NR_CPUS]; static void etm4_set_default_config(struct etmv4_config *config); @@ -1365,6 +1366,30 @@ static void etm4_fixup_wrong_ccitmin(struct etmv4_drvdata *drvdata) } }
+static int etm4_init_pm_save(struct device *dev, struct etmv4_drvdata *drvdata) +{ + if (etm4x_is_ete(drvdata)) { + /* + * Always do PM save for ETE. It always uses system registers + * which will be lost on CPU power down. + */ + 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; + } + + return 0; +} + static void etm4_init_arch_data(void *info) { u32 etmidr0; @@ -2247,6 +2272,9 @@ static int etm4_add_coresight_dev(struct etm4_init_arg *init_arg) return -ENOMEM;
etm4_set_default(&drvdata->config); + ret = etm4_init_pm_save(dev, drvdata); + if (ret) + return ret;
pdata = coresight_get_platform_data(dev); if (IS_ERR(pdata)) @@ -2305,17 +2333,6 @@ 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);
pm_save_enable is a global module parameter used as a user input, but at the same time is modified on probe. There are some theoretical scenarios where the DT for one device says to save and another says not to which result in one device not allocating save state memory but later trying to save if probing happens in a certain order. We also couldn't warn if the module parameter is used for ETE because the input value is overwritten, then for the next device it looks like the user had set a value triggering a warning.
Fix it by treating the module parameter strictly as user input and adding a new per device pm_save boolean, and then add the warning that couldn't be added before.
Signed-off-by: James Clark james.clark@linaro.org --- drivers/hwtracing/coresight/coresight-etm4x-core.c | 22 ++++++++++++++++------ drivers/hwtracing/coresight/coresight-etm4x.h | 1 + 2 files changed, 17 insertions(+), 6 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index a7fb680dd383..915f348620d8 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -1366,20 +1366,30 @@ static void etm4_fixup_wrong_ccitmin(struct etmv4_drvdata *drvdata) } }
+/* + * Take the global pm_save_enable module argument and setup the CPU PM save + * setting for this device. + */ static int etm4_init_pm_save(struct device *dev, struct etmv4_drvdata *drvdata) { if (etm4x_is_ete(drvdata)) { + if (pm_save_enable) + dev_warn_once(dev, "pm_save_enable module option is only for ETM4\n"); + /* * Always do PM save for ETE. It always uses system registers * which will be lost on CPU power down. */ - pm_save_enable = PARAM_PM_SAVE_SELF_HOSTED; + drvdata->pm_save = true; } 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; + drvdata->pm_save = coresight_loses_context_with_cpu(dev); + } else if (pm_save_enable == PARAM_PM_SAVE_SELF_HOSTED) { + drvdata->pm_save = true; + } else { + drvdata->pm_save = false; }
- if (pm_save_enable != PARAM_PM_SAVE_NEVER) { + if (drvdata->pm_save) { drvdata->save_state = devm_kmalloc(dev, sizeof(struct etmv4_save_state), GFP_KERNEL); @@ -2037,7 +2047,7 @@ static int etm4_cpu_save(struct etmv4_drvdata *drvdata) { int ret = 0;
- if (pm_save_enable != PARAM_PM_SAVE_SELF_HOSTED) + if (!drvdata->pm_save) return 0;
/* @@ -2152,7 +2162,7 @@ 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->pm_save) return;
if (coresight_get_mode(drvdata->csdev)) diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h index 89d81ce4e04e..6472677f3098 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x.h +++ b/drivers/hwtracing/coresight/coresight-etm4x.h @@ -1078,6 +1078,7 @@ struct etmv4_drvdata { bool lpoverride : 1; bool skip_power_up : 1; bool paused : 1; + bool pm_save : 1; u64 trfcr; struct etmv4_config config; struct etmv4_save_state *save_state;
-
James Clark