linux-kernel - Re: [PATCH] coresight: tmc-etr: Don't fail probe when non-secure access is disabled

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Message-ID: <382193a4-4f30-d804-47da-a9c705b6bee5@arm.com>
Date:   Sun, 27 Aug 2023 22:37:38 +0100
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     Yabin Cui <yabinc@...gle.com>, Mike Leach <mike.leach@...aro.org>,
        James Clark <james.clark@....com>, Leo Yan <leo.yan@...aro.org>
Cc:     Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] coresight: tmc-etr: Don't fail probe when non-secure
 access is disabled

On 26/08/2023 00:39, Yabin Cui wrote:
> Because the non-secure access can be enabled later on some devices.

How can this be enabled ? Why not enable it before probing the ETR ?
How can a user know if this has been done or not ? It is asking for
trouble to continue without this.

Suzuki

> 
> Signed-off-by: Yabin Cui <yabinc@...gle.com>
> ---
>   drivers/hwtracing/coresight/coresight-tmc-core.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
> index c106d142e632..5ebfd12b627b 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-core.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
> @@ -370,7 +370,7 @@ static int tmc_etr_setup_caps(struct device *parent, u32 devid, void *dev_caps)
>   	struct tmc_drvdata *drvdata = dev_get_drvdata(parent);
>   
>   	if (!tmc_etr_has_non_secure_access(drvdata))
> -		return -EACCES;
> +		dev_warn(parent, "TMC ETR doesn't have non-secure access\n");
>   
>   	/* Set the unadvertised capabilities */
>   	tmc_etr_init_caps(drvdata, (u32)(unsigned long)dev_caps);