linux-kernel - Re: [PATCH 1/1] arm64: defconfig: Add Coresight as module

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Message-ID: <1867fb58-cb96-5d82-2518-e7212b6849a0@arm.com>
Date:   Thu, 22 Sep 2022 10:26:23 +0100
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     James Clark <james.clark@....com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Mark Brown <broonie@...nel.org>
Cc:     coresight@...ts.linaro.org, catalin.marinas@....com,
        linux-arm-kernel@...ts.infradead.org, mike.leach@...aro.org,
        leo.yan@...aro.org, linux-kernel@...r.kernel.org,
        Will Deacon <will@...nel.org>
Subject: Re: [PATCH 1/1] arm64: defconfig: Add Coresight as module

On 22/09/2022 10:04, James Clark wrote:
> 
> 
> On 21/09/2022 17:46, Mathieu Poirier wrote:
>> On Wed, Sep 21, 2022 at 04:26:59PM +0100, Mark Brown wrote:
>>> On Wed, Sep 21, 2022 at 03:05:35PM +0100, James Clark wrote:
>>>
>>>> +CONFIG_CORESIGHT_CTI=m
>>>> +CONFIG_CORESIGHT_CTI_INTEGRATION_REGS=y
>>>
>>
>> I agree - integration registers should not be enabled by default.
>>
>>> Do we want this turned on by default?  According to the
>>> description it's a bit dangerous and it's exposed via sysfs
>>> rather than debugfs.
>>
>>
> 
> Should I disable just CONFIG_CORESIGHT_CTI_INTEGRATION_REGS or
> CONFIG_CORESIGHT_CTI as well? There are other writable registers exposed
> via sysfs outside of these two options, so I wanted to check if it's
> just the integration registers that are the issue.

It is good/fine to keep CORESIGHT_CTI. But you may remove the 
INTEGRATION_REGS. They are there for "verification" of the CTI
integration on the SoC. We added them only for the platform
bring up purposes.

Suzuki