Re: [PATCH] Add system-cache-controller to the list of generic node names

From: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
To: Rob Herring <robh+dt@kernel.org>
Cc: Mailing List <devicetree-spec@vger.kernel.org>,
	devicetree@vger.kernel.org, Stephen Boyd <swboyd@chromium.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Rajendra Nayak <rnayak@codeaurora.org>
Subject: Re: [PATCH] Add system-cache-controller to the list of generic node names
Date: Fri, 01 Oct 2021 09:53:33 +0530	[thread overview]
Message-ID: <84f956f861e55bbfc1df0761ce7b4786@codeaurora.org> (raw)
In-Reply-To: <CAL_Jsq+vkpigu3P+dkAVXT7nypnJA_R8LBPGgj9wERcCW6P36w@mail.gmail.com>

On 2021-09-30 19:03, Rob Herring wrote:
> On Wed, Sep 29, 2021 at 11:06 PM Sai Prakash Ranjan
> <saiprakash.ranjan@codeaurora.org> wrote:
>> 
>> On 2021-09-29 18:12, Rob Herring wrote:
>> > On Wed, Sep 29, 2021 at 12:26 AM Sai Prakash Ranjan
>> > <saiprakash.ranjan@codeaurora.org> wrote:
>> >>
>> >> System Cache Controller (Last Level Cache Controller/LLCC) does not
>> >> have a cache-level associated with it as enforced by the already
>> >> existing 'cache-controller' node name, so add system-cache-controller
>> >> to the list of generic node names as decided on the lkml in [1][2]
>> >> and already being used in the dts for sometime now.
>> >>
>> >> [1]
>> >> https://lore.kernel.org/lkml/5dcd8588.1c69fb81.2528a.3460@mx.google.com/
>> >> [2]
>> >> https://lore.kernel.org/lkml/cover.1573814758.git.saiprakash.ranjan@codeaurora.org/
>> >>
>> >> Cc: Stephen Boyd <swboyd@chromium.org>
>> >> Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
>> >> Cc: Rajendra Nayak <rnayak@codeaurora.org>
>> >> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
>> >> ---
>> >>  source/chapter2-devicetree-basics.rst | 1 +
>> >>  1 file changed, 1 insertion(+)
>> >>
>> >> diff --git a/source/chapter2-devicetree-basics.rst
>> >> b/source/chapter2-devicetree-basics.rst
>> >> index 40be22192b2f..c06c5063c68b 100644
>> >> --- a/source/chapter2-devicetree-basics.rst
>> >> +++ b/source/chapter2-devicetree-basics.rst
>> >> @@ -276,6 +276,7 @@ name should be one of the following choices:
>> >>     * sram-controller
>> >>     * ssi-controller
>> >>     * syscon
>> >> +   * system-cache-controller
>> >
>> > I don't want to encourage others to use this over 'cache-controller'
>> > and the standard binding.
>> >
>> 
>> Right, but why would others use this over cache-controller? This is
>> supposed
>> to be used only for last level cache controllers where there is no
>> cache-level
>> associated with it like in the system cache controller/LLCC found in 
>> QTI
>> SoCs.
> 
> I don't agree there's never a level.
> 

More like it isn't used for now.

> Using the cache binding will be necessary if you want to populate the
> kernel's cache info. If your caches have MPAM support, they are going
> to need to follow the cache binding as well.
> 
>> Also you had acked the corresponding change in the DT binding for LLCC
>> [1].
> 
> Yes, but that doesn't mean it belongs in the spec. Maybe when we have
> more than 1 case that will change, but for now I don't think it should
> be in the spec.
> 

All right, will drop this change for now.

Thanks,
Sai

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