linux-kernel - Re: [PATCH v3 2/4] cacheinfo: Check cache properties are present in DT

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Message-ID: <20230413195032.bw3yu7a6puqziinx@bogus>
Date:   Thu, 13 Apr 2023 20:50:32 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     Pierre Gondois <pierre.gondois@....com>,
        linux-kernel@...r.kernel.org, Sudeep Holla <sudeep.holla@....com>,
        Radu Rendec <rrendec@...hat.com>,
        Alexandre Ghiti <alexghiti@...osinc.com>,
        Conor Dooley <conor.dooley@...rochip.com>,
        Will Deacon <will@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Palmer Dabbelt <palmer@...osinc.com>,
        Gavin Shan <gshan@...hat.com>
Subject: Re: [PATCH v3 2/4] cacheinfo: Check cache properties are present in
 DT

On Thu, Apr 13, 2023 at 11:16:37AM -0700, Florian Fainelli wrote:
> On 4/13/23 02:14, Pierre Gondois wrote:
> > If a Device Tree (DT) is used, the presence of cache properties is
> > assumed. Not finding any is not considered. For arm64 platforms,
> > cache information can be fetched from the clidr_el1 register.
> > Checking whether cache information is available in the DT
> > allows to switch to using clidr_el1.
> > 
> > init_of_cache_level()
> > \-of_count_cache_leaves()
> > will assume there a 2 cache leaves (L1 data/instruction caches), which
> > can be different from clidr_el1 information.
> > 
> > cache_setup_of_node() tries to read cache properties in the DT.
> > If there are none, this is considered a success. Knowing no
> > information was available would allow to switch to using clidr_el1.
> > 
> > Fixes: de0df442ee49 ("cacheinfo: Check 'cache-unified' property to count cache leaves")
> > Reported-by: Alexandre Ghiti <alexghiti@...osinc.com>
> > Link: https://lore.kernel.org/all/20230404-hatred-swimmer-6fecdf33b57a@spud/
> > Signed-off-by: Pierre Gondois <pierre.gondois@....com>
> 
> Humm, it would appear that the cache levels and topology is still provided,
> despite the lack of cache properties in the Device Tree which is intended by
> this patch set however we lost the size/ways/sets information, could we not
> complement the missing properties here?
> 

I am confused. How and from where the information was fetched before this
change ?

> If this is out of the scope of what you are doing:
> 
> Tested-by: Florian Fainelli <f.fainelli@...il.com>
>

Just looking at the lscpu output before and after, it looks something is
broken. What am I missing here ?

-- 
Regards,
Sudeep