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Message-ID: <CAJ9a7VgJu4mzcbTpd=TytQnu0vPFZeS8uyNb9swamTpNXxnBew@mail.gmail.com>
Date: Tue, 22 Oct 2024 10:49:32 +0100
From: Mike Leach <mike.leach@...aro.org>
To: Suzuki K Poulose <suzuki.poulose@....com>
Cc: Mao Jinlong <quic_jinlmao@...cinc.com>, James Clark <james.clark@....com>,
Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>, coresight@...ts.linaro.org,
linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v5 3/3] coresight: dummy: Add static trace id support for
dummy source
On Mon, 21 Oct 2024 at 13:36, Suzuki K Poulose <suzuki.poulose@....com> wrote:
>
> On 21/10/2024 13:31, Suzuki K Poulose wrote:
> > On 18/10/2024 04:22, Mao Jinlong wrote:
> >> Some dummy source has static trace id configured in HW and it cannot
> >> be changed via software programming. Configure the trace id in device
> >> tree and reserve the id when device probe.
> >>
> >> Signed-off-by: Mao Jinlong <quic_jinlmao@...cinc.com>
> >> ---
> >> .../sysfs-bus-coresight-devices-dummy-source | 15 +++++
> >> drivers/hwtracing/coresight/coresight-dummy.c | 59 +++++++++++++++++--
> >> 2 files changed, 70 insertions(+), 4 deletions(-)
> >> create mode 100644 Documentation/ABI/testing/sysfs-bus-coresight-
> >> devices-dummy-source
> >>
> >> diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-
> >> dummy-source b/Documentation/ABI/testing/sysfs-bus-coresight-devices-
> >> dummy-source
> >> new file mode 100644
> >> index 000000000000..c7d975e75d85
> >> --- /dev/null
> >> +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-dummy-source
> >> @@ -0,0 +1,15 @@
> >> +What: /sys/bus/coresight/devices/dummy_source<N>/enable_source
> >> +Date: Oct 2024
> >> +KernelVersion: 6.13
> >> +Contact: Mao Jinlong <quic_jinlmao@...cinc.com>
> >> +Description: (RW) Enable/disable tracing of dummy source. A sink
> >> should be activated
> >> + before enabling the source. The path of coresight components
> >> linking
> >> + the source to the sink is configured and managed
> >> automatically by the
> >> + coresight framework.
> >> +
> >> +What: /sys/bus/coresight/devices/dummy_source<N>/traceid
> >> +Date: Oct 2024
> >> +KernelVersion: 6.13
> >> +Contact: Mao Jinlong <quic_jinlmao@...cinc.com>
> >> +Description: (R) Show the trace ID that will appear in the trace
> >> stream
> >> + coming from this trace entity.
> >> diff --git a/drivers/hwtracing/coresight/coresight-dummy.c b/drivers/
> >> hwtracing/coresight/coresight-dummy.c
> >> index bb85fa663ffc..602a7e89e311 100644
> >> --- a/drivers/hwtracing/coresight/coresight-dummy.c
> >> +++ b/drivers/hwtracing/coresight/coresight-dummy.c
> >> @@ -11,10 +11,12 @@
> >> #include <linux/pm_runtime.h>
> >> #include "coresight-priv.h"
> >> +#include "coresight-trace-id.h"
> >> struct dummy_drvdata {
> >> struct device *dev;
> >> struct coresight_device *csdev;
> >> + u8 traceid;
> >> };
> >> DEFINE_CORESIGHT_DEVLIST(source_devs, "dummy_source");
> >> @@ -72,6 +74,32 @@ static const struct coresight_ops dummy_sink_cs_ops
> >> = {
> >> .sink_ops = &dummy_sink_ops,
> >> };
> >> +/* User can get the trace id of dummy source from this node. */
> >> +static ssize_t traceid_show(struct device *dev,
> >> + struct device_attribute *attr, char *buf)
> >> +{
> >> + unsigned long val;
> >> + struct dummy_drvdata *drvdata = dev_get_drvdata(dev->parent);
> >> +
> >> + val = drvdata->traceid;
> >> + return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
sysfs_emit() is the convention moving forwards - this handles all the
PAGE_SIZE issues automatically
> >> +}
> >> +static DEVICE_ATTR_RO(traceid);
> >> +
> >> +static struct attribute *coresight_dummy_attrs[] = {
> >> + &dev_attr_traceid.attr,
> >> + NULL,
> >> +};
> >> +
> >> +static const struct attribute_group coresight_dummy_group = {
> >> + .attrs = coresight_dummy_attrs,
> >> +};
> >> +
> >> +static const struct attribute_group *coresight_dummy_groups[] = {
> >> + &coresight_dummy_group,
> >> + NULL,
> >> +};
> >> +
> >> static int dummy_probe(struct platform_device *pdev)
> >> {
> >> struct device *dev = &pdev->dev;
> >> @@ -79,6 +107,11 @@ static int dummy_probe(struct platform_device *pdev)
> >> struct coresight_platform_data *pdata;
> >> struct dummy_drvdata *drvdata;
> >> struct coresight_desc desc = { 0 };
> >> + int ret, trace_id;
> >> +
> >> + drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
> >> + if (!drvdata)
> >> + return -ENOMEM;
> >> if (of_device_is_compatible(node, "arm,coresight-dummy-source")) {
> >> @@ -90,6 +123,25 @@ static int dummy_probe(struct platform_device *pdev)
> >> desc.subtype.source_subtype =
> >> CORESIGHT_DEV_SUBTYPE_SOURCE_OTHERS;
> >> desc.ops = &dummy_source_cs_ops;
> >> + desc.groups = coresight_dummy_groups;
> >> +
> >> + ret = coresight_get_static_trace_id(dev, &trace_id);
> >> + if (!ret) {
> >> + /* Get the static id if id is set in device tree. */
> >> + ret = coresight_trace_id_get_static_system_id(trace_id);
>
> This may be worth an error message, it is a rare one. Othewise, there is
> no clue on what caused the failure. Or have a specific error code as a
> result ?
>
The called function does actually emit an error message - but a
comment to that effect would clarify this.
> >> + if (ret < 0)
> >> + return ret;
>
> e.g., return -EBUSY ? /* Device or resource not available */
>
> >> +
> >> + } else {
> >> + /* Get next available id if id is not set in device tree. */
> >> + trace_id = coresight_trace_id_get_system_id();
> >> + if (trace_id < 0) {
> >> + ret = trace_id;
> >> + return ret;
> >> + }
> >> + }
> >> + drvdata->traceid = (u8)trace_id;
> >> +
> >> } else if (of_device_is_compatible(node, "arm,coresight-dummy-
> >> sink")) {
> >> desc.name = coresight_alloc_device_name(&sink_devs, dev);
> >> if (!desc.name)
> >> @@ -108,10 +160,6 @@ static int dummy_probe(struct platform_device *pdev)
> >> return PTR_ERR(pdata);
> >> pdev->dev.platform_data = pdata;
> >> - drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
> >> - if (!drvdata)
> >> - return -ENOMEM;
> >> -
> >> drvdata->dev = &pdev->dev;
> >> platform_set_drvdata(pdev, drvdata);
>
> Additionally we should drop the system_id if registering the coresight
> device fails.
>
>
> Suzuki
>
> >> @@ -131,7 +179,10 @@ static void dummy_remove(struct platform_device
> >> *pdev)
> >> {
> >> struct dummy_drvdata *drvdata = platform_get_drvdata(pdev);
> >> struct device *dev = &pdev->dev;
> >> + struct device_node *node = dev->of_node;
> >
> > ^^ Why is this needed ? The rest looks fine to me
> >
> >> + if (IS_VALID_CS_TRACE_ID(drvdata->traceid))
> >> + coresight_trace_id_put_system_id(drvdata->traceid);
> >> pm_runtime_disable(dev);
> >> coresight_unregister(drvdata->csdev);
> >> }
> >
>
Mike
--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK
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