linux-kernel - Re: [PATCH v3 4/9] coresight: Appropriately disable programming clocks

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Message-ID: <f565a64e-62d8-4cb3-b1b1-6de981b1052a@arm.com>
Date: Tue, 24 Jun 2025 09:53:00 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: Leo Yan <leo.yan@....com>, Suzuki K Poulose <suzuki.poulose@....com>
Cc: Mike Leach <mike.leach@...aro.org>, James Clark <james.clark@...aro.org>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, coresight@...ts.linaro.org,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 4/9] coresight: Appropriately disable programming
 clocks



On 09/06/25 10:08 PM, Leo Yan wrote:
> On Mon, Jun 09, 2025 at 05:11:21PM +0100, Suzuki Kuruppassery Poulose wrote:
>> On 09/06/2025 17:00, Leo Yan wrote:
>>> Some CoreSight components have programming clocks (pclk) and are enabled
>>> using clk_get() and clk_prepare_enable().  However, in many cases, these
>>> clocks are not disabled when modules exit and only released by clk_put().
>>>
>>> To fix the issue, this commit refactors coresight_get_enable_apb_pclk()
>>> by replacing clk_get() and clk_prepare_enable() with
>>> devm_clk_get_enabled() for enabling APB clock.  Callers are updated
>>> to reuse the returned error value.
>>>
>>> With the change, programming clocks are managed as resources in driver
>>> model layer, allowing clock cleanup to be handled automatically.  As a
>>> result, manual cleanup operations are no longer needed and are removed
>>> from the Coresight drivers.
>>>
>>> Fixes: 73d779a03a76 ("coresight: etm4x: Change etm4_platform_driver driver for MMIO devices")
>>
>> This looks suspicious. This patch covers a lot of components, but the
>> above commit is only affecting ETMv4 ?
> 
> Since commit 73d779a03a76 is the earliest patch that introduced the
> issue, it has been selected as the fix tag. We assume this will cover
> any subsequent changes that have the same issue.

Although I am not still sure about this patch actually requiring a
'Fixes:' tag as it just transitions into the device managed clocks
rather than fixing an existing issue. But choosing the first commit
makes sense as Leo has explained.

> 
>> The patch as such looks good to me.
> 
> Thanks for review!
> 
>> Suzuki
>