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Message-ID: <b40b3512-1782-80ad-2bcc-6a7558fc64a2@arm.com>
Date:   Fri, 19 May 2023 13:38:19 +0100
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Subject: Re: [PATCH V3 3/6] coresight: etm4x: Drop pid argument from
 etm4_probe()
To:     Anshuman Khandual <anshuman.khandual@arm.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        coresight@lists.linaro.org
Cc:     Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>,
        Steve Clevenger <scclevenger@os.amperecomputing.com>,
        Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        Russell King <linux@armlinux.org.uk>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Len Brown <lenb@kernel.org>,
        Sudeep Holla <sudeep.holla@arm.com>,
        Lorenzo Pieralisi <lpieralisi@kernel.org>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Mike Leach <mike.leach@linaro.org>,
        Leo Yan <leo.yan@linaro.org>, devicetree@vger.kernel.org,
        linux-acpi@vger.kernel.org
References: <20230519052149.1367814-1-anshuman.khandual@arm.com>
 <20230519052149.1367814-4-anshuman.khandual@arm.com>
From:   Suzuki K Poulose <suzuki.poulose@arm.com>
In-Reply-To: <20230519052149.1367814-4-anshuman.khandual@arm.com>
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Precedence: bulk

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