linux-kernel - Re: [PATCH v4 04/10] coresight: Appropriately disable programming clocks

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <8285b872-ecfa-42a6-9ead-e84ae409f79d@arm.com>
Date: Tue, 22 Jul 2025 14:25:23 +0100
From: Suzuki K Poulose <suzuki.poulose@....com>
To: Leo Yan <leo.yan@....com>
Cc: Mike Leach <mike.leach@...aro.org>, James Clark <james.clark@...aro.org>,
 Anshuman Khandual <anshuman.khandual@....com>,
 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 v4 04/10] coresight: Appropriately disable programming
 clocks

On 21/07/2025 14:59, Leo Yan wrote:
> On Mon, Jul 21, 2025 at 12:40:38PM +0100, Suzuki Kuruppassery Poulose wrote:
>> On 21/07/2025 11:48, Leo Yan wrote:
>>> On Mon, Jul 21, 2025 at 10:15:22AM +0100, Suzuki Kuruppassery Poulose wrote:
>>>
>>> [...]
>>>
>>>>> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
>>>>> index 4ac65c68bbf44b98db22c3dad2d83a224ce5278e..dd2b4cc7a2b70cf060a3207548fe80e3824c489f 100644
>>>>> --- a/include/linux/coresight.h
>>>>> +++ b/include/linux/coresight.h
>>>>> @@ -480,26 +480,16 @@ static inline bool is_coresight_device(void __iomem *base)
>>>>>      * Returns:
>>>>>      *
>>>>>      * clk   - Clock is found and enabled
>>>>> - * NULL  - clock is not found
>>>>
>>>> This is still valid, right ?
>>>
>>> No. Since this patch uses devm_clk_get_enabled() to get a clock, if the
>>> pclk is not found, it returns -ENOENT (see of_parse_clkspec()).
>>>
>>> Only the optional clock APIs (e.g., devm_clk_get_optional_enabled())
>>> return a NULL pointer instead of -ENOENT when the clock is not found.
>>
>> This will break ACPI based systems, as we may not have a "pclk" described
>> for them. We should be able to tolerate "no pclk"
> 
> Get it. How about change the code like below?
> 
>    static inline struct clk *coresight_get_enable_apb_pclk(struct device *dev)
>    {
>        struct clk *pclk;
> 
>        pclk = devm_clk_get_enabled(dev, "apb_pclk");
>        if (IS_ERR(pclk))
>            pclk = devm_clk_get_enabled(dev, "apb");
> 
>        /* Tolerate no pclk for ACPI device */
>        if ((pclk == ERR_PTR(-ENOENT)) && has_acpi_companion(dev))

That might be OK, please could you test this out ?




>            return NULL;
> 
>        return pclk;
>    }