linux-kernel - Re: [PATCH v2 7/9] coresight: Refactor out buffer allocation function for ETR

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Message-ID: <CAJ9a7VjgbgaufYiVR+N62WKOVVKU=0iEoxai3JLEiwXcMDsv7g@mail.gmail.com>
Date:   Tue, 21 Mar 2023 18:01:50 +0000
From:   Mike Leach <mike.leach@...aro.org>
To:     James Clark <james.clark@....com>
Cc:     coresight@...ts.linaro.org,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Leo Yan <leo.yan@...aro.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 7/9] coresight: Refactor out buffer allocation function
 for ETR

On Fri, 10 Mar 2023 at 16:07, James Clark <james.clark@....com> wrote:
>
> When CATU is moved to the generic enable/disable path system in the
> next commit, it will need to call into ETR and get it to pre-allocate
> its buffer so add a function for it.
>
> No functional changes
>
> Signed-off-by: James Clark <james.clark@....com>
> ---
>  .../hwtracing/coresight/coresight-tmc-etr.c   | 50 ++++++++++++++++---
>  drivers/hwtracing/coresight/coresight-tmc.h   |  2 +
>  2 files changed, 45 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index 223081dc3ad4..cb9621003aef 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> @@ -1169,7 +1169,7 @@ void tmc_etr_disable_hw(struct tmc_drvdata *drvdata)
>         drvdata->etr_buf = NULL;
>  }
>
> -static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev)
> +static struct etr_buf *tmc_etr_get_sysfs_buffer(struct coresight_device *csdev)
>  {
>         int ret = 0;
>         unsigned long flags;
> @@ -1192,7 +1192,7 @@ static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev)
>                 /* Allocate memory with the locks released */
>                 free_buf = new_buf = tmc_etr_setup_sysfs_buf(drvdata);
>                 if (IS_ERR(new_buf))
> -                       return PTR_ERR(new_buf);
> +                       return new_buf;
>
>                 /* Let's try again */
>                 spin_lock_irqsave(&drvdata->spinlock, flags);
> @@ -1223,17 +1223,33 @@ static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev)
>                 drvdata->sysfs_buf = new_buf;
>         }
>
> -       ret = tmc_etr_enable_hw(drvdata, drvdata->sysfs_buf);
> -       if (!ret) {
> -               drvdata->mode = CS_MODE_SYSFS;
> -               atomic_inc(csdev->refcnt);
> -       }
>  out:
>         spin_unlock_irqrestore(&drvdata->spinlock, flags);
>
>         /* Free memory outside the spinlock if need be */
>         if (free_buf)
>                 tmc_etr_free_sysfs_buf(free_buf);
> +       return ret ? ERR_PTR(ret) : drvdata->sysfs_buf;
> +}
> +
> +static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev)
> +{
> +       int ret;
> +       unsigned long flags;
> +       struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
> +       struct etr_buf *sysfs_buf = tmc_etr_get_sysfs_buffer(csdev);
> +
> +       if (IS_ERR(sysfs_buf))
> +               return PTR_ERR(sysfs_buf);
> +
> +       spin_lock_irqsave(&drvdata->spinlock, flags);
> +       ret = tmc_etr_enable_hw(drvdata, sysfs_buf);
> +       if (!ret) {
> +               drvdata->mode = CS_MODE_SYSFS;
> +               atomic_inc(csdev->refcnt);
> +       }
> +
> +       spin_unlock_irqrestore(&drvdata->spinlock, flags);
>
>         if (!ret)
>                 dev_dbg(&csdev->dev, "TMC-ETR enabled\n");
> @@ -1241,6 +1257,26 @@ static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev)
>         return ret;
>  }
>
> +struct etr_buf *tmc_etr_get_buffer(struct coresight_device *csdev,
> +                                  enum cs_mode mode, void *data)
> +{
> +       struct perf_output_handle *handle = data;
> +       struct etr_perf_buffer *etr_perf;
> +
> +       switch (mode) {
> +       case CS_MODE_SYSFS:
> +               return tmc_etr_get_sysfs_buffer(csdev);
> +       case CS_MODE_PERF:
> +               etr_perf = etm_perf_sink_config(handle);
> +               if (WARN_ON(!etr_perf || !etr_perf->etr_buf))
> +                       return ERR_PTR(-EINVAL);
> +               return etr_perf->etr_buf;
> +       default:
> +               return ERR_PTR(-EINVAL);
> +       }
> +}
> +EXPORT_SYMBOL_GPL(tmc_etr_get_buffer);
> +
>  /*
>   * alloc_etr_buf: Allocate ETR buffer for use by perf.
>   * The size of the hardware buffer is dependent on the size configured
> diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
> index 01c0382a29c0..b97da39652d2 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc.h
> +++ b/drivers/hwtracing/coresight/coresight-tmc.h
> @@ -332,5 +332,7 @@ struct coresight_device *tmc_etr_get_catu_device(struct tmc_drvdata *drvdata);
>
>  void tmc_etr_set_catu_ops(const struct etr_buf_operations *catu);
>  void tmc_etr_remove_catu_ops(void);
> +struct etr_buf *tmc_etr_get_buffer(struct coresight_device *csdev,
> +                                  enum cs_mode mode, void *data);
>
>  #endif
> --
> 2.34.1
>

Reviewed by: Mike Leach <mike.leach@...aro.org>
-- 
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK