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Date: Wed, 5 Jun 2024 04:44:07 +0000
From: Linu Cherian <lcherian@...vell.com>
To: James Clark <james.clark@....com>
CC: "linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"coresight@...ts.linaro.org"
<coresight@...ts.linaro.org>,
"linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>,
"robh+dt@...nel.org" <robh+dt@...nel.org>,
"krzysztof.kozlowski+dt@...aro.org" <krzysztof.kozlowski+dt@...aro.org>,
"conor+dt@...nel.org" <conor+dt@...nel.org>,
"devicetree@...r.kernel.org"
<devicetree@...r.kernel.org>,
Sunil Kovvuri Goutham <sgoutham@...vell.com>,
George Cherian <gcherian@...vell.com>,
"suzuki.poulose@....com"
<suzuki.poulose@....com>,
"mike.leach@...aro.org" <mike.leach@...aro.org>
Subject: RE: [EXTERNAL] Re: [PATCH v8 6/7] coresight: tmc: Stop trace capture
on FlIn
Hi James,
> -----Original Message-----
> From: James Clark <james.clark@....com>
> Sent: Friday, May 31, 2024 3:47 PM
> To: Linu Cherian <lcherian@...vell.com>
> Cc: linux-arm-kernel@...ts.infradead.org; coresight@...ts.linaro.org; linux-
> kernel@...r.kernel.org; robh+dt@...nel.org;
> krzysztof.kozlowski+dt@...aro.org; conor+dt@...nel.org;
> devicetree@...r.kernel.org; Sunil Kovvuri Goutham
> <sgoutham@...vell.com>; George Cherian <gcherian@...vell.com>;
> suzuki.poulose@....com; mike.leach@...aro.org
> Subject: [EXTERNAL] Re: [PATCH v8 6/7] coresight: tmc: Stop trace capture on
> FlIn
>
> Prioritize security for external emails: Confirm sender and content safety
> before clicking links or opening attachments
>
> ----------------------------------------------------------------------
>
>
> On 31/05/2024 05:27, Linu Cherian wrote:
> > Configure TMC ETR and ETF to flush and stop trace capture on FlIn
> > event based on sysfs attribute,
> > /sys/bus/coresight/devices/tmc_etXn/stop_on_flush.
> >
> > Signed-off-by: Linu Cherian <lcherian@...vell.com>
> > ---
> > Changelog from v7:
> > * Honour stop_on_flush sysfs attribute for perf sessions as well.
> > This allows user to start trace sessions using perf method as
> > well to use the Coresight kernel panic support.
> >
> > .../hwtracing/coresight/coresight-tmc-core.c | 31
> +++++++++++++++++++
> > .../hwtracing/coresight/coresight-tmc-etf.c | 18 ++++++++---
> > .../hwtracing/coresight/coresight-tmc-etr.c | 18 ++++++++---
> > drivers/hwtracing/coresight/coresight-tmc.h | 4 +++
> > 4 files changed, 61 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c
> > b/drivers/hwtracing/coresight/coresight-tmc-core.c
> > index aaa9de9f4cd2..24edd9d750c3 100644
> > --- a/drivers/hwtracing/coresight/coresight-tmc-core.c
> > +++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
> > @@ -452,9 +452,40 @@ static ssize_t buffer_size_store(struct device
> > *dev,
> >
> > static DEVICE_ATTR_RW(buffer_size);
> >
> > +static ssize_t stop_on_flush_show(struct device *dev,
> > + struct device_attribute *attr, char *buf) {
> > + struct tmc_drvdata *drvdata = dev_get_drvdata(dev->parent);
> > +
> > + return sprintf(buf, "%#x\n", drvdata->stop_on_flush); }
> > +
> > +static ssize_t stop_on_flush_store(struct device *dev,
> > + struct device_attribute *attr,
> > + const char *buf, size_t size)
> > +{
> > + int ret;
> > + u8 val;
> > + struct tmc_drvdata *drvdata = dev_get_drvdata(dev->parent);
> > +
> > + ret = kstrtou8(buf, 0, &val);
> > + if (ret)
> > + return ret;
> > + if (val)
> > + drvdata->stop_on_flush = true;
> > + else
> > + drvdata->stop_on_flush = false;
> > +
> > + return size;
> > +}
> > +
> > +static DEVICE_ATTR_RW(stop_on_flush);
> > +
> > +
> > static struct attribute *coresight_tmc_attrs[] = {
> > &dev_attr_trigger_cntr.attr,
> > &dev_attr_buffer_size.attr,
> > + &dev_attr_stop_on_flush.attr,
> > NULL,
> > };
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c
> > b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> > index 655c0c0ba54b..1529b9cc210a 100644
> > --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
> > +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> > @@ -19,6 +19,7 @@ static int tmc_set_etf_buffer(struct
> > coresight_device *csdev, static int __tmc_etb_enable_hw(struct
> > tmc_drvdata *drvdata) {
> > int rc = 0;
> > + u32 ffcr;
> >
> > CS_UNLOCK(drvdata->base);
> >
> > @@ -32,10 +33,12 @@ static int __tmc_etb_enable_hw(struct
> tmc_drvdata *drvdata)
> > }
> >
> > writel_relaxed(TMC_MODE_CIRCULAR_BUFFER, drvdata->base +
> TMC_MODE);
> > - writel_relaxed(TMC_FFCR_EN_FMT | TMC_FFCR_EN_TI |
> > - TMC_FFCR_FON_FLIN | TMC_FFCR_FON_TRIG_EVT |
> > - TMC_FFCR_TRIGON_TRIGIN,
> > - drvdata->base + TMC_FFCR);
> > +
> > + ffcr = TMC_FFCR_EN_FMT | TMC_FFCR_EN_TI |
> TMC_FFCR_FON_FLIN |
> > + TMC_FFCR_FON_TRIG_EVT | TMC_FFCR_TRIGON_TRIGIN;
> > + if (drvdata->stop_on_flush_en)
> > + ffcr |= TMC_FFCR_STOP_ON_FLUSH;
> > + writel_relaxed(ffcr, drvdata->base + TMC_FFCR);
> >
> > writel_relaxed(drvdata->trigger_cntr, drvdata->base + TMC_TRG);
> > tmc_enable_hw(drvdata);
> > @@ -225,7 +228,8 @@ static int tmc_enable_etf_sink_sysfs(struct
> coresight_device *csdev)
> > used = true;
> > drvdata->buf = buf;
> > }
> > -
> > + if (drvdata->stop_on_flush)
> > + drvdata->stop_on_flush_en = true;
>
> Does this do anything different than only using stop_on_flush in
> __tmc_etr_enable_hw()?
>
> Seems like stop_on_flush_en == stop_on_flush whenever
> stop_on_flush_en is read, so you might as well just read stop_on_flush and
> get rid of the _en copy?
>
Ack.
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