[PATCH] coresight: cpu-debug: control default behavior via Kconfig

From: Brian Norris
Date: Fri Sep 03 2021 - 21:29:10 EST


Debugfs is nice and so are module parameters, but
* debugfs doesn't take effect early (e.g., if drivers are locking up
before user space gets anywhere)
* module parameters either add a lot to the kernel command line, or
else take effect late as well (if you build =m and configure in
/etc/modprobe.d/)

So in the same spirit as these
CONFIG_PANIC_ON_OOPS (also available via cmdline or modparam)
CONFIG_INTEL_IOMMU_DEFAULT_ON (also available via cmdline)
add a new Kconfig option.

Module parameters and debugfs can still override.

Signed-off-by: Brian Norris <briannorris@xxxxxxxxxxxx>
---

drivers/hwtracing/coresight/Kconfig | 13 +++++++++++++
drivers/hwtracing/coresight/coresight-cpu-debug.c | 2 +-
2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
index f026e5c0e777..8b638eb3cb7d 100644
--- a/drivers/hwtracing/coresight/Kconfig
+++ b/drivers/hwtracing/coresight/Kconfig
@@ -150,6 +150,19 @@ config CORESIGHT_CPU_DEBUG
To compile this driver as a module, choose M here: the
module will be called coresight-cpu-debug.

+config CORESIGHT_CPU_DEBUG_DEFAULT_ON
+ bool "Enable CoreSight CPU Debug by default
+ depends on CORESIGHT_CPU_DEBUG
+ help
+ Say Y here to enable the CoreSight Debug panic-debug by default. This
+ can also be enabled via debugfs, but this ensures the debug feature
+ is enabled as early as possible.
+
+ Has the same effect as setting coresight_cpu_debug.enable=1 on the
+ kernel command line.
+
+ Say N if unsure.
+
config CORESIGHT_CTI
tristate "CoreSight Cross Trigger Interface (CTI) driver"
depends on ARM || ARM64
diff --git a/drivers/hwtracing/coresight/coresight-cpu-debug.c b/drivers/hwtracing/coresight/coresight-cpu-debug.c
index 00de46565bc4..8845ec4b4402 100644
--- a/drivers/hwtracing/coresight/coresight-cpu-debug.c
+++ b/drivers/hwtracing/coresight/coresight-cpu-debug.c
@@ -105,7 +105,7 @@ static DEFINE_PER_CPU(struct debug_drvdata *, debug_drvdata);
static int debug_count;
static struct dentry *debug_debugfs_dir;

-static bool debug_enable;
+static bool debug_enable = IS_ENABLED(CONFIG_CORESIGHT_CPU_DEBUG_DEFAULT_ON);
module_param_named(enable, debug_enable, bool, 0600);
MODULE_PARM_DESC(enable, "Control to enable coresight CPU debug functionality");

--
2.33.0.153.gba50c8fa24-goog