linux-kernel - Re: [PATCH 2/3] cacheinfo: Check cache properties are present in DT

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Message-ID: <8296483f-4056-4e64-890f-3f676edb3c3d@spud>
Date:   Mon, 27 Mar 2023 15:13:59 +0100
From:   Conor Dooley <conor.dooley@...rochip.com>
To:     Pierre Gondois <pierre.gondois@....com>
CC:     <linux-kernel@...r.kernel.org>, Radu Rendec <rrendec@...hat.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Akihiko Odaki <akihiko.odaki@...nix.com>,
        Palmer Dabbelt <palmer@...osinc.com>,
        Gavin Shan <gshan@...hat.com>,
        Jeremy Linton <jeremy.linton@....com>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 2/3] cacheinfo: Check cache properties are present in DT

On Mon, Mar 27, 2023 at 01:59:50PM +0200, 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.
> 
> Signed-off-by: Pierre Gondois <pierre.gondois@....com>

> +static bool of_check_cache_nodes(struct device_node *np)
> +{
> +	struct device_node *next;
> +
> +	if (of_property_read_bool(np, "cache-size")   ||
> +	    of_property_read_bool(np, "i-cache-size") ||
> +	    of_property_read_bool(np, "d-cache-size") ||
> +	    of_property_read_bool(np, "cache-unified"))
> +		return true;
> +

Rob's been purging use of the of_property_read family of functions
recently [1], should this use of_property_present() instead?

Cheers,
Conor.

1 - https://lore.kernel.org/all/?q=Use+of_property_present%28%29+for+testing+DT+property+presence+f%3Arob

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