linux-kernel - Re: [PATCH 2/7] coresight: Convert disclaim functions to take a struct cs

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Message-ID: <20250317182957.GL2487211@e132581.arm.com>
Date: Mon, 17 Mar 2025 18:29:57 +0000
From: Leo Yan <leo.yan@....com>
To: James Clark <james.clark@...aro.org>
Cc: lcherian@...vell.com, coresight@...ts.linaro.org,
	Mike Leach <mike.leach@...aro.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-stm32@...md-mailman.stormreply.com
Subject: Re: [PATCH 2/7] coresight: Convert disclaim functions to take a
 struct cs_access

On Mon, Mar 17, 2025 at 11:36:40AM +0000, James Clark wrote:
> 
> 
> On 13/03/2025 2:54 pm, Leo Yan wrote:
> > On Tue, Feb 11, 2025 at 10:39:38AM +0000, James Clark wrote:
> > 
> > [...]
> > 
> > >   static inline bool coresight_is_claimed_any(struct coresight_device *csdev)
> > >   {
> > > -       return coresight_read_claim_tags(csdev) != 0;
> > > +       return coresight_read_claim_tags(&csdev->access) != 0;
> > >   }
> > 
> > Likewise other claim functions, can coresight_is_claimed_any() change its
> > argument type from struct coresight_device to struct csdev_access?
> 
> I only wanted to change the ones that I had to. I think we should prioritize
> passing csdev as much as possible in the coresight framework to make
> everything consistent. Otherwise it's extra churn for no benefit, and if we
> need something from csdev here in the future we'll have to change this one
> back again.

The function coresight_is_claimed_any() has been deleted in a later
patch.  So this is fine for me.

In theory, claim tags are low level operations and don't need a
CoreSight device context, I prefer we can keep them as simple as
possible.

With this series, we can see coresight_claim_device() and
coresight_disclaim_device() are inconsistent for their parameters:
one is using "struct coresight_device *" and another is
"struct csdev_access *".  Maybe we just proceed to use csdev_access
for all claim tag functions?

If later we need to use a CoreSight device context when operating
claim tags, it means we might have different scenarios and we can
handle that separately.

Thanks,
Leo