Hi Suzuki,

On Mon, Aug 06, 2018 at 02:41:48PM +0100, Suzuki K Poulose wrote:
> Prepare the etb10 driver to return errors in enabling
> the device.
> 
> Cc: Mathieu Poirier <mathieu.poir...@linaro.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poul...@arm.com>
> ---
>  drivers/hwtracing/coresight/coresight-etb10.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-etb10.c 
> b/drivers/hwtracing/coresight/coresight-etb10.c
> index 9fd77fd..37d2c88 100644
> --- a/drivers/hwtracing/coresight/coresight-etb10.c
> +++ b/drivers/hwtracing/coresight/coresight-etb10.c
> @@ -107,7 +107,7 @@ static unsigned int etb_get_buffer_depth(struct 
> etb_drvdata *drvdata)
>       return depth;
>  }
>  
> -static void etb_enable_hw(struct etb_drvdata *drvdata)
> +static void __etb_enable_hw(struct etb_drvdata *drvdata)
>  {
>       int i;
>       u32 depth;
> @@ -135,6 +135,12 @@ static void etb_enable_hw(struct etb_drvdata *drvdata)
>       CS_LOCK(drvdata->base);
>  }
>  
> +static int etb_enable_hw(struct etb_drvdata *drvdata)
> +{
> +     __etb_enable_hw(drvdata);
> +     return 0;
> +}
> +
>  static int etb_enable(struct coresight_device *csdev, u32 mode, void *data)
>  {
>       int ret = 0;
> @@ -150,7 +156,7 @@ static int etb_enable(struct coresight_device *csdev, u32 
> mode, void *data)
>       if (mode == CS_MODE_PERF) {
>               ret = etb_set_buffer(csdev, (struct perf_output_handle *)data);
>               if (ret)
> -                     goto out;
> +                     return ret;
>       }
>  
>       val = local_cmpxchg(&drvdata->mode,
> @@ -172,12 +178,14 @@ static int etb_enable(struct coresight_device *csdev, 
> u32 mode, void *data)
>               goto out;
>  
>       spin_lock_irqsave(&drvdata->spinlock, flags);
> -     etb_enable_hw(drvdata);
> +     ret = etb_enable_hw(drvdata);
>       spin_unlock_irqrestore(&drvdata->spinlock, flags);
>  
> -out:
> -     if (!ret)
> +     if (ret)
> +             local_cmpxchg(&drvdata->mode, mode, CS_MODE_DISABLED);
> +     else

I also have to do hackish things with my work on
CPU-wide trace scenarios because drvdata->mode is of type local_t.  Instead of
living with it I'll send out a patch later today that moves it to a u32 like ETF
and ETR.

Please look at it and if you're happy, add it to this patchset and do your 
modifications on top of it.

Thanks,
Mathieu

>               dev_dbg(drvdata->dev, "ETB enabled\n");
> +
>       return ret;
>  }
>  
> -- 
> 2.7.4
> 

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