linux-kernel - Re: [PATCH 0/9] coresight: change some driver' spinlock type to raw_spinlock

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Message-ID:
 <GV1PR08MB10521E2C28D14B8A0FCB3A59EFB292@GV1PR08MB10521.eurprd08.prod.outlook.com>
Date: Thu, 28 Nov 2024 11:48:15 +0000
From: Yeo Reum Yun <YeoReum.Yun@....com>
To: James Clark <james.clark@...aro.org>, Suzuki Poulose
	<Suzuki.Poulose@....com>, "mike.leach@...aro.org" <mike.leach@...aro.org>
CC: "coresight@...ts.linaro.org" <coresight@...ts.linaro.org>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-rt-devel@...ts.linux.dev"
	<linux-rt-devel@...ts.linux.dev>, nd <nd@....com>,
	"alexander.shishkin@...ux.intel.com" <alexander.shishkin@...ux.intel.com>,
	"bigeasy@...utronix.de" <bigeasy@...utronix.de>, "clrkwllms@...nel.org"
	<clrkwllms@...nel.org>, "rostedt@...dmis.org" <rostedt@...dmis.org>
Subject: Re: [PATCH 0/9] coresight: change some driver' spinlock type to
 raw_spinlock_t

Hi James,

> Can TPIU be used as a sink with Perf? If so that one is missing the update.

No. IIRC from feedback from Suzuki, TPIU not used in perf mode.

> Makes me wonder if something like a "perf_component" flag in
> coresight_device or a #define would make sense. Then the lock type gets
> auto picked. Seems like in a few years we will have completely forgotten
> why some of the coresight locks are raw and others aren't.

I think later then do define new flags to solve
sharing data between perf and sysfs (i.e. etm4x config),

it would be more resonable seperate config for perf and sysfs.
so that, sysfs shared data could be manged with inside of SYSFS subsystem
and it can have sepearte lock to synchronize under SYSFS.
it doesn't need to define that lock type as raw_spin_lock_t and
solve the data modifying between perf and sysfs setup.

But, This is another story.

And I'll seperate this patchset to two part.
     - Change locktype from spin_lock_t to raw_spin_lock_t
     - Apply scoped_guard 

so that backward portiable.

Thanks for your review again :)