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Message-ID: <1a093631-ded2-4ef3-b72c-3aaffd1b0739@arm.com>
Date: Fri, 31 May 2024 11:16:42 +0100
From: James Clark <james.clark@....com>
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, sgoutham@...vell.com, gcherian@...vell.com,
suzuki.poulose@....com, mike.leach@...aro.org
Subject: Re: [PATCH v8 6/7] coresight: tmc: Stop trace capture on FlIn
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?
> ret = tmc_etb_enable_hw(drvdata);
> if (!ret) {
> coresight_set_mode(csdev, CS_MODE_SYSFS);
> @@ -288,6 +292,8 @@ static int tmc_enable_etf_sink_perf(struct coresight_device *csdev, void *data)
> break;
> }
>
> + if (drvdata->stop_on_flush)
> + drvdata->stop_on_flush_en = true;
> ret = tmc_etb_enable_hw(drvdata);
> if (!ret) {
> /* Associate with monitored process. */
> @@ -349,6 +355,8 @@ static int tmc_disable_etf_sink(struct coresight_device *csdev)
> tmc_etb_disable_hw(drvdata);
> /* Dissociate from monitored process. */
> drvdata->pid = -1;
> + /* Reset stop on flush */
> + drvdata->stop_on_flush_en = false;
> coresight_set_mode(csdev, CS_MODE_DISABLED);
>
> spin_unlock_irqrestore(&drvdata->spinlock, flags);
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index 74f53972ce3c..bf2d0932e205 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> @@ -1059,7 +1059,7 @@ static void tmc_sync_etr_buf(struct tmc_drvdata *drvdata)
>
> static int __tmc_etr_enable_hw(struct tmc_drvdata *drvdata)
> {
> - u32 axictl, sts;
> + u32 axictl, sts, ffcr;
> struct etr_buf *etr_buf = drvdata->etr_buf;
> int rc = 0;
>
> @@ -1105,10 +1105,12 @@ static int __tmc_etr_enable_hw(struct tmc_drvdata *drvdata)
> writel_relaxed(sts, drvdata->base + TMC_STS);
> }
>
> - 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);
>
> @@ -1313,6 +1315,8 @@ static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev)
> goto out;
> }
>
> + if (drvdata->stop_on_flush)
> + drvdata->stop_on_flush_en = true;
> ret = tmc_etr_enable_hw(drvdata, sysfs_buf);
> if (!ret) {
> coresight_set_mode(csdev, CS_MODE_SYSFS);
> @@ -1758,6 +1762,8 @@ static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, void *data)
> goto unlock_out;
> }
>
> + if (drvdata->stop_on_flush)
> + drvdata->stop_on_flush_en = true;
> rc = tmc_etr_enable_hw(drvdata, etr_perf->etr_buf);
> if (!rc) {
> /* Associate with monitored process. */
> @@ -1808,6 +1814,8 @@ static int tmc_disable_etr_sink(struct coresight_device *csdev)
> tmc_etr_disable_hw(drvdata);
> /* Dissociate from monitored process. */
> drvdata->pid = -1;
> + /* Reset stop on flush */
> + drvdata->stop_on_flush_en = false;
> coresight_set_mode(csdev, CS_MODE_DISABLED);
> /* Reset perf specific data */
> drvdata->perf_buf = NULL;
> diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
> index 528174283ecc..81eadb384b83 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc.h
> +++ b/drivers/hwtracing/coresight/coresight-tmc.h
> @@ -205,6 +205,8 @@ struct tmc_resrv_buf {
> * @spinlock: only one at a time pls.
> * @pid: Process ID of the process being monitored by the session
> * that is using this component.
> + * @stop_on_flush: Stop on flush trigger user configuration.
> + * @stop_on_flush_en: Stop on flush enable flag
> * @buf: Snapshot of the trace data for ETF/ETB.
> * @etr_buf: details of buffer used in TMC-ETR
> * @len: size of the available trace for ETF/ETB.
> @@ -238,6 +240,8 @@ struct tmc_drvdata {
> spinlock_t spinlock;
> pid_t pid;
> bool reading;
> + bool stop_on_flush;
> + bool stop_on_flush_en;
> union {
> char *buf; /* TMC ETB */
> struct etr_buf *etr_buf; /* TMC ETR */
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