Re: [PATCH v2 01/11] coresight-etm4x: Adding CoreSight ETM4x driver

From: Paul Bolle
Date: Thu Apr 30 2015 - 17:30:11 EST


On Wed, 2015-04-29 at 11:16 -0600, Mathieu Poirier wrote:
> --- a/drivers/hwtracing/coresight/Kconfig
> +++ b/drivers/hwtracing/coresight/Kconfig

> +config CORESIGHT_SOURCE_ETM4X
> + bool "CoreSight Embedded Trace Macrocell 4.x driver"
> + depends on ARM64
> + select CORESIGHT_LINKS_AND_SINKS
> + help
> + This driver provides support for the ETM4.x tracer module, tracing the
> + instructions that a processor is executing. This is primarily useful
> + for instruction level tracing. Depending on the implemented version
> + data tracing may also be available.

(Please add an empty line here.)

> endif

> --- a/drivers/hwtracing/coresight/Makefile
> +++ b/drivers/hwtracing/coresight/Makefile

> +obj-$(CONFIG_CORESIGHT_SOURCE_ETM4X) += coresight-etm4x.o

CORESIGHT_SOURCE_ETM4X is a bool symbol, so coresight-etm4x.o can never
be part of a module, right?

(If I'm wrong, we're done here.)

> --- /dev/null
> +++ b/drivers/hwtracing/coresight/coresight-etm4x.c

> +#include <linux/module.h>

Is this include needed?

> +static struct amba_driver etm4x_driver = {
> + .drv = {
> + .name = "coresight-etm4x",
> + .owner = THIS_MODULE,

For built-in code this is basically equivalent to NULL (see
include/linux/export.h).

> + },
> + .probe = etm4_probe,
> + .remove = etm4_remove,
> + .id_table = etm4_ids,
> +};
> +
> +module_amba_driver(etm4x_driver);

In a message I sent a short while ago, I suggested that for built-in
only code this is equivalent to calling
amba_driver_register(&etm4x_driver);

from within a function marked with some sort of *initcall(). Please
double check.

> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("CoreSight Embedded Trace Macrocell v4 driver");

These macros will be effectively be preprocessed away for built-in only
code.

(There is also a reference to module_param_named(). I don't know by
heart how that works for built-in only code, sorry.)


Paul Bolle

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