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Subject[PATCH 06/16] coresight: cti: remove pm_runtime_get_sync() from CPU hotplug
Date
From: Tingwei Zhang <tingwei@codeaurora.org>

Below BUG is triggered by call pm_runtime_get_sync() in
cti_cpuhp_enable_hw(). It's in CPU hotplug callback with interrupt
disabled. Pm_runtime_get_sync() calls clock driver to enable clock
which could sleep. Remove pm_runtime_get_sync() in cti_cpuhp_enable_hw()
since pm_runtime_get_sync() is called in cti_enabld and pm_runtime_put()
is called in cti_disabled. No need to increase pm count when CPU gets
online since it's not decreased when CPU is offline.

[ 105.800279] BUG: scheduling while atomic: swapper/1/0/0x00000002
[ 105.800290] Modules linked in:
[ 105.800327] CPU: 1 PID: 0 Comm: swapper/1 Tainted: G W
5.9.0-rc1-gff1304be0a05-dirty #21
[ 105.800337] Hardware name: Thundercomm Dragonboard 845c (DT)
[ 105.800353] Call trace:
[ 105.800414] dump_backtrace+0x0/0x1d4
[ 105.800439] show_stack+0x14/0x1c
[ 105.800462] dump_stack+0xc0/0x100
[ 105.800490] __schedule_bug+0x58/0x74
[ 105.800523] __schedule+0x590/0x65c
[ 105.800538] schedule+0x78/0x10c
[ 105.800553] schedule_timeout+0x188/0x250
[ 105.800585] qmp_send.constprop.10+0x12c/0x1b0
[ 105.800599] qmp_qdss_clk_prepare+0x18/0x20
[ 105.800622] clk_core_prepare+0x48/0xd4
[ 105.800639] clk_prepare+0x20/0x34
[ 105.800663] amba_pm_runtime_resume+0x54/0x90
[ 105.800695] __rpm_callback+0xdc/0x138
[ 105.800709] rpm_callback+0x24/0x78
[ 105.800724] rpm_resume+0x328/0x47c
[ 105.800739] __pm_runtime_resume+0x50/0x74
[ 105.800768] cti_starting_cpu+0x40/0xa4
[ 105.800795] cpuhp_invoke_callback+0x84/0x1e0
[ 105.800814] notify_cpu_starting+0x9c/0xb8
[ 105.800834] secondary_start_kernel+0xd8/0x164
[ 105.800933] CPU1: Booted secondary processor 0x0000000100 [0x517f803c]

Fixes: e9b880581d55 ("coresight: cti: Add CPU Hotplug handling to CTI driver")
Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
drivers/hwtracing/coresight/coresight-cti.c | 3 ---
1 file changed, 3 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-cti.c b/drivers/hwtracing/coresight/coresight-cti.c
index d6fea6efec71..c4e9cc7034ab 100644
--- a/drivers/hwtracing/coresight/coresight-cti.c
+++ b/drivers/hwtracing/coresight/coresight-cti.c
@@ -141,9 +141,7 @@ static int cti_enable_hw(struct cti_drvdata *drvdata)
static void cti_cpuhp_enable_hw(struct cti_drvdata *drvdata)
{
struct cti_config *config = &drvdata->config;
- struct device *dev = &drvdata->csdev->dev;

- pm_runtime_get_sync(dev->parent);
spin_lock(&drvdata->spinlock);
config->hw_powered = true;

@@ -163,7 +161,6 @@ static void cti_cpuhp_enable_hw(struct cti_drvdata *drvdata)
/* did not re-enable due to no claim / no request */
cti_hp_not_enabled:
spin_unlock(&drvdata->spinlock);
- pm_runtime_put(dev->parent);
}

/* disable hardware */
--
2.25.1
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