Re: [PATCH v8 21/24] coresight: cti: allow cti to be built as a module

Mike Leach
2020-08-17T19:16:26Z

Hi,

On Mon, 17 Aug 2020 at 18:13, Mathieu Poirier
<mathieu.poirier@linaro.org> wrote:
>
> On Fri, Aug 07, 2020 at 07:11:50PM +0800, Tingwei Zhang wrote:
> > Allow to build coresight-cti as a module, for ease of development.
> >
> > - Kconfig becomes a tristate, to allow =m
> > - append -core to source file name to allow module to
> > be called coresight-cti by the Makefile
> > - add an cti_remove function, for module unload
> > - move cti_remove_conn_xrefs to cti_remove
> > - add a MODULE_DEVICE_TABLE for autoloading on boot
> >
> > Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>
> > Tested-by: Mike Leach <mike.leach@linaro.org>
>
> Mike,
>
> Please add a "Reviewed-by" tag once you have reviewed this patch.
>

Sorry - not sure of the protocol - assumed that my tested-by implied
reviewed by.

Anyway...

Reviewed-by Mike Leach <mike.leach@linaro.org>

> > ---
> > drivers/hwtracing/coresight/Kconfig | 5 ++++-
> > drivers/hwtracing/coresight/Makefile | 4 ++--
> > .../{coresight-cti.c => coresight-cti-core.c} | 19 ++++++++++++++++++-
> > .../hwtracing/coresight/coresight-platform.c | 1 +
> > drivers/hwtracing/coresight/coresight.c | 1 +
> > 5 files changed, 26 insertions(+), 4 deletions(-)
> > rename drivers/hwtracing/coresight/{coresight-cti.c => coresight-cti-core.c} (98%)
> >
> > diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
> > index f31778dd0b5d..b04aae2ceecc 100644
> > --- a/drivers/hwtracing/coresight/Kconfig
> > +++ b/drivers/hwtracing/coresight/Kconfig
> > @@ -136,7 +136,7 @@ config CORESIGHT_CPU_DEBUG
> > module will be called coresight-cpu-debug.
> >
> > config CORESIGHT_CTI
> > - bool "CoreSight Cross Trigger Interface (CTI) driver"
> > + tristate "CoreSight Cross Trigger Interface (CTI) driver"
> > depends on ARM || ARM64
> > help
> > This driver provides support for CoreSight CTI and CTM components.
> > @@ -147,6 +147,9 @@ config CORESIGHT_CTI
> > halt compared to disabling sources and sinks normally in driver
> > software.
> >
> > + To compile this driver as a module, choose M here: the
> > + module will be called coresight-cti.
> > +
> > config CORESIGHT_CTI_INTEGRATION_REGS
> > bool "Access CTI CoreSight Integration Registers"
> > depends on CORESIGHT_CTI
> > diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
> > index f2a568b969c4..0359d5a1588f 100644
> > --- a/drivers/hwtracing/coresight/Makefile
> > +++ b/drivers/hwtracing/coresight/Makefile
> > @@ -19,6 +19,6 @@ coresight-etm4x-y := coresight-etm4x-core.o coresight-etm4x-sysfs.o
> > obj-$(CONFIG_CORESIGHT_STM) += coresight-stm.o
> > obj-$(CONFIG_CORESIGHT_CPU_DEBUG) += coresight-cpu-debug.o
> > obj-$(CONFIG_CORESIGHT_CATU) += coresight-catu.o
> > -obj-$(CONFIG_CORESIGHT_CTI) += coresight-cti.o \
> > - coresight-cti-platform.o \
> > +obj-$(CONFIG_CORESIGHT_CTI) += coresight-cti.o
> > +coresight-cti-y := coresight-cti-core.o coresight-cti-platform.o \
> > coresight-cti-sysfs.o
>
> Please align "coresight-cti-sysfs.o" with "coresight-cti-core.o". The same
> should be done for the etm3x driver.
>
> > diff --git a/drivers/hwtracing/coresight/coresight-cti.c b/drivers/hwtracing/coresight/coresight-cti-core.c
> > similarity index 98%
> > rename from drivers/hwtracing/coresight/coresight-cti.c
> > rename to drivers/hwtracing/coresight/coresight-cti-core.c
> > index 6bb06c5715db..ca31da6cf1c0 100644
> > --- a/drivers/hwtracing/coresight/coresight-cti.c
> > +++ b/drivers/hwtracing/coresight/coresight-cti-core.c
> > @@ -838,7 +838,6 @@ static void cti_device_release(struct device *dev)
> > struct cti_drvdata *ect_item, *ect_tmp;
> >
> > mutex_lock(&ect_mutex);
> > - cti_remove_conn_xrefs(drvdata);
> > cti_pm_release(drvdata);
> >
> > /* remove from the list */
> > @@ -853,6 +852,18 @@ static void cti_device_release(struct device *dev)
> > if (drvdata->csdev_release)
> > drvdata->csdev_release(dev);
> > }
> > +static int __exit cti_remove(struct amba_device *adev)
> > +{
> > + struct cti_drvdata *drvdata = dev_get_drvdata(&adev->dev);
> > +
> > + mutex_lock(&ect_mutex);
> > + cti_remove_conn_xrefs(drvdata);
> > + mutex_unlock(&ect_mutex);
>
> The changelog point out this change but now _why_ it is done - please revise.
>

By the time the system calls device_release, all the sysfs links have
gone so trying to remove them results in errors / crash. Not obvious
when the drivers were built in as this would be called while the
system was powering down, but very much noticeable when removing the
CTI moduie from a running system.

Regards

Mike

> > +
> > + coresight_unregister(drvdata->csdev);
> > +
> > + return 0;
> > +}
> >
> > static int cti_probe(struct amba_device *adev, const struct amba_id *id)
> > {
> > @@ -972,6 +983,7 @@ static const struct amba_id cti_ids[] = {
> > CS_AMBA_UCI_ID(0x000bb9ed, uci_id_cti), /* Coresight CTI (SoC 600) */
> > { 0, 0},
> > };
> > +MODULE_DEVICE_TABLE(amba, cti_ids);
> >
> > static struct amba_driver cti_driver = {
> > .drv = {
> > @@ -980,6 +992,7 @@ static struct amba_driver cti_driver = {
> > .suppress_bind_attrs = true,
> > },
> > .probe = cti_probe,
> > + .remove = cti_remove,
> > .id_table = cti_ids,
> > };
> >
> > @@ -1002,3 +1015,7 @@ static void __exit cti_exit(void)
> >
> > module_init(cti_init);
> > module_exit(cti_exit);
> > +
> > +MODULE_AUTHOR("Mike Leach <mike.leach@linaro.org>");
> > +MODULE_DESCRIPTION("Arm CoreSight CTI Driver");
> > +MODULE_LICENSE("GPL v2");
> > diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c
> > index bfd44231d7ad..635d55c1d580 100644
> > --- a/drivers/hwtracing/coresight/coresight-platform.c
> > +++ b/drivers/hwtracing/coresight/coresight-platform.c
> > @@ -75,6 +75,7 @@ coresight_find_csdev_by_fwnode(struct fwnode_handle *r_fwnode)
> > }
> > return csdev;
> > }
> > +EXPORT_SYMBOL_GPL(coresight_find_csdev_by_fwnode);
> >
> > #ifdef CONFIG_OF
> > static inline bool of_coresight_legacy_ep_is_input(struct device_node *ep)
> > diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
> > index 8dcd73ea33b4..f9566d667261 100644
> > --- a/drivers/hwtracing/coresight/coresight.c
> > +++ b/drivers/hwtracing/coresight/coresight.c
> > @@ -289,6 +289,7 @@ void coresight_set_assoc_ectdev_mutex(struct coresight_device *csdev,
> > csdev->ect_dev = ect_csdev;
> > mutex_unlock(&coresight_mutex);
> > }
> > +EXPORT_SYMBOL_GPL(coresight_set_assoc_ectdev_mutex);
> >
> > static int coresight_enable_sink(struct coresight_device *csdev,
> > u32 mode, void *data)
> > --
> > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> > a Linux Foundation Collaborative Project
> >

--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK