Re: [PATCH V3 3/6] coresight: etm4x: Drop pid argument from etm4_probe()

Suzuki K Poulose
2023-05-19T12:38:27Z

On 19/05/2023 06:21, Anshuman Khandual wrote:
> Coresight device pid can be retrieved from its iomem base address, which is
> stored in 'struct etm4x_drvdata'. This drops pid argument from etm4_probe()
> and 'struct etm4_init_arg'. Instead etm4_check_arch_features() derives the
> coresight device pid with a new helper coresight_get_pid(), right before it
> is consumed in etm4_hisi_match_pid().
>
> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> Cc: Mike Leach <mike.leach@linaro.org>
> Cc: Leo Yan <leo.yan@linaro.org>
> Cc: coresight@lists.linaro.org
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
> .../coresight/coresight-etm4x-core.c | 29 ++++++++++---------
> include/linux/coresight.h | 12 ++++++++
> 2 files changed, 27 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> index 748d2ef53cb0..914ef6eb85d1 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -66,7 +66,6 @@ static u64 etm4_get_access_type(struct etmv4_config *config);
> static enum cpuhp_state hp_online;
>
> struct etm4_init_arg {
> - unsigned int pid;
> struct device *dev;
> struct csdev_access *csa;
> };
> @@ -370,9 +369,17 @@ static void etm4_disable_arch_specific(struct etmv4_drvdata *drvdata)
> }
>
> static void etm4_check_arch_features(struct etmv4_drvdata *drvdata,
> - unsigned int id)
> + struct csdev_access *csa)
> {
> - if (etm4_hisi_match_pid(id))
> + /*
> + * coresight_get_pid() fetches device PID from the iomem
> + * register based accesses, which cannot be performed on
> + * system instruction based devices.
> + */

Minor nit: Please fix the comment to say something like :

/*
* TRCPIDR* registers are not required for ETMs with system
* instructions. They must be identified by the MIDR+REVIDRs.
* Skip the TRCPID checks for now.
*/

Rest looks good to me.

Suzuki