[PATCH] coresight: etm4x: Fix number of resources check for ETM 4.3 and above.
mathieu.poirier at linaro.org
Tue Sep 15 12:45:14 EDT 2020
On Tue, Sep 15, 2020 at 12:36:21PM +0100, Mike Leach wrote:
> The initialisation code checks TRCIDR4 to determine the number of resource
> selectors available on the system. Since ETM v 4.3, the value 0 has a
> different meaning. This patch takes into account this change.
> Signed-off-by: Mike Leach <mike.leach at linaro.org>
> drivers/hwtracing/coresight/coresight-etm4x.c | 8 +++++++-
> drivers/hwtracing/coresight/coresight-etm4x.h | 3 +++
> 2 files changed, 10 insertions(+), 1 deletion(-)
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
> index 00c9f0bb8b1a..be687276704c 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x.c
> @@ -742,8 +742,14 @@ static void etm4_init_arch_data(void *info)
> * The number of resource pairs conveyed by the HW starts at 0, i.e a
> * value of 0x0 indicate 1 resource pair, 0x1 indicate two and so on.
> * As such add 1 to the value of NUMRSPAIR for a better representation.
> + *
> + * For ETM v4.3 and later, 0x0 means 0, and no pairs are available -
> + * the default TRUE and FALSE resource selectors are omitted.
> + * Otherwise for values 0x1 and above the number is N + 1 as per v4.2.
That's a weird implementation... I had to double check the documentation to convince me
that your comment was correct before applying the patch.
> - drvdata->nr_resource = BMVAL(etmidr4, 16, 19) + 1;
> + drvdata->nr_resource = BMVAL(etmidr4, 16, 19);
> + if ((drvdata->arch < ETM4X_ARCH_4V3) || (drvdata->nr_resource > 0))
> + drvdata->nr_resource += 1;
> * NUMSSCC, bits[23:20] the number of single-shot
> * comparator control for tracing. Read any status regs as these
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
> index 5259f96fd28a..eefc7371c6c4 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
> @@ -200,6 +200,9 @@
> /* NS MON (EL3) mode never implemented */
> #define ETM_EXLEVEL_NS_VICTLR_MASK GENMASK(22, 20)
> +/* Interpretation of resource numbers change at ETM v4.3 architecture */
> +#define ETM4X_ARCH_4V3 0x43
> * struct etmv4_config - configuration information related to an ETMv4
> * @mode: Controls various modes supported by this ETM.
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