Re: [PATCH 03/13] coresight: tmc-etb/etf: Prepare to handle errors enabling

Mathieu Poirier
2018-08-15T19:22:55Z

On Mon, Aug 06, 2018 at 02:41:45PM +0100, Suzuki K Poulose wrote:
> Prepare to handle errors in enabling the hardware and
> report it back to the core driver.
>
> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> ---
> drivers/hwtracing/coresight/coresight-tmc-etf.c | 71 +++++++++++++++----------
> 1 file changed, 44 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> index 4156c95..ceb4b30 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> @@ -15,7 +15,7 @@
> static int tmc_set_etf_buffer(struct coresight_device *csdev,
> struct perf_output_handle *handle);
>
> -static void tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
> +static void __tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
> {
> CS_UNLOCK(drvdata->base);
>
> @@ -34,6 +34,12 @@ static void tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
> CS_LOCK(drvdata->base);
> }
>
> +static int tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
> +{
> + __tmc_etb_enable_hw(drvdata);
> + return 0;
> +}
> +
> static void tmc_etb_dump_hw(struct tmc_drvdata *drvdata)
> {
> char *bufp;
> @@ -76,7 +82,7 @@ static void tmc_etb_disable_hw(struct tmc_drvdata *drvdata)
> CS_LOCK(drvdata->base);
> }
>
> -static void tmc_etf_enable_hw(struct tmc_drvdata *drvdata)
> +static void __tmc_etf_enable_hw(struct tmc_drvdata *drvdata)
> {
> CS_UNLOCK(drvdata->base);
>
> @@ -92,6 +98,12 @@ static void tmc_etf_enable_hw(struct tmc_drvdata *drvdata)
> CS_LOCK(drvdata->base);
> }
>
> +static int tmc_etf_enable_hw(struct tmc_drvdata *drvdata)
> +{
> + __tmc_etf_enable_hw(drvdata);
> + return 0;
> +}
> +
> static void tmc_etf_disable_hw(struct tmc_drvdata *drvdata)
> {
> CS_UNLOCK(drvdata->base);
> @@ -174,8 +186,12 @@ static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev)
> drvdata->buf = buf;
> }
>
> - drvdata->mode = CS_MODE_SYSFS;
> - tmc_etb_enable_hw(drvdata);
> + ret = tmc_etb_enable_hw(drvdata);
> + if (!ret)
> + drvdata->mode = CS_MODE_SYSFS;
> + else
> + /* Free up the buffer if we failed to enable */
> + used = false;
> out:
> spin_unlock_irqrestore(&drvdata->spinlock, flags);
>
> @@ -194,27 +210,25 @@ static int tmc_enable_etf_sink_perf(struct coresight_device *csdev, void *data)
> struct perf_output_handle *handle = data;
>
> spin_lock_irqsave(&drvdata->spinlock, flags);
> - if (drvdata->reading) {
> + do {
> ret = -EINVAL;
> - goto out;
> - }
> + if (drvdata->reading)
> + break;
> + /*
> + * In Perf mode there can be only one writer per sink. There
> + * is also no need to continue if the ETB/ETF is already
> + * operated from sysFS.
> + */
> + if (drvdata->mode != CS_MODE_DISABLED)
> + break;
>
> - /*
> - * In Perf mode there can be only one writer per sink. There
> - * is also no need to continue if the ETB/ETR is already operated
> - * from sysFS.
> - */
> - if (drvdata->mode != CS_MODE_DISABLED) {
> - ret = -EINVAL;
> - goto out;
> - }
> -
> - ret = tmc_set_etf_buffer(csdev, handle);
> - if (!ret) {
> - drvdata->mode = CS_MODE_PERF;
> - tmc_etb_enable_hw(drvdata);
> - }
> -out:
> + ret = tmc_set_etf_buffer(csdev, handle);
> + if (ret)
> + break;
> + ret = tmc_etb_enable_hw(drvdata);
> + if (!ret)
> + drvdata->mode = CS_MODE_PERF;
> + } while (0);
> spin_unlock_irqrestore(&drvdata->spinlock, flags);
>
> return ret;
> @@ -271,6 +285,7 @@ static void tmc_disable_etf_sink(struct coresight_device *csdev)
> static int tmc_enable_etf_link(struct coresight_device *csdev,
> int inport, int outport)
> {
> + int ret;
> unsigned long flags;
> struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
>
> @@ -280,11 +295,13 @@ static int tmc_enable_etf_link(struct coresight_device *csdev,
> return -EBUSY;
> }
>
> - tmc_etf_enable_hw(drvdata);
> - drvdata->mode = CS_MODE_SYSFS;
> + ret = tmc_etf_enable_hw(drvdata);
> + if (!ret)
> + drvdata->mode = CS_MODE_SYSFS;
> spin_unlock_irqrestore(&drvdata->spinlock, flags);
>
> - dev_dbg(drvdata->dev, "TMC-ETF enabled\n");
> + if (!ret)
> + dev_dbg(drvdata->dev, "TMC-ETF enabled\n");
> return 0;

We need to tell the caller if an error as occured:

return ret;

> }
>
> @@ -579,7 +596,7 @@ int tmc_read_unprepare_etb(struct tmc_drvdata *drvdata)
> * can't be NULL.
> */
> memset(drvdata->buf, 0, drvdata->size);
> - tmc_etb_enable_hw(drvdata);
> + __tmc_etb_enable_hw(drvdata);
> } else {
> /*
> * The ETB/ETF is not tracing and the buffer was just read.
> --
> 2.7.4
>