linux-kernel - Re: [PATCH v6 02/12] drivers: base: cacheinfo: setup DT cache properties early

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Message-ID: <15884ccc-2cfb-da91-5844-369d8237175d@arm.com>
Date:   Wed, 17 Jan 2018 12:51:31 -0600
From:   Jeremy Linton <jeremy.linton@....com>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     linux-acpi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        hanjun.guo@...aro.org, lorenzo.pieralisi@....com,
        rjw@...ysocki.net, will.deacon@....com, catalin.marinas@....com,
        gregkh@...uxfoundation.org, viresh.kumar@...aro.org,
        mark.rutland@....com, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, jhugo@...eaurora.org,
        wangxiongfeng2@...wei.com, Jonathan.Zhang@...ium.com,
        ahs3@...hat.com, Jayachandran.Nair@...ium.com,
        austinwc@...eaurora.org, lenb@...nel.org, vkilari@...eaurora.org,
        morten.rasmussen@....com, Palmer Dabbelt <palmer@...ive.com>,
        Albert Ou <albert@...ive.com>
Subject: Re: [PATCH v6 02/12] drivers: base: cacheinfo: setup DT cache
 properties early

Hi,

On 01/17/2018 12:20 PM, Sudeep Holla wrote:
> 
> 
> On 16/01/18 21:07, Jeremy Linton wrote:
>> Hi,
>>
>> On 01/15/2018 06:33 AM, Sudeep Holla wrote:
>>> On Fri, Jan 12, 2018 at 06:59:10PM -0600, Jeremy Linton wrote:
>>>> The original intent in cacheinfo was that an architecture
>>>> specific populate_cache_leaves() would probe the hardware
>>>> and then cache_shared_cpu_map_setup() and
>>>> cache_override_properties() would provide firmware help to
>>>> extend/expand upon what was probed. Arm64 was really
>>>> the only architecture that was working this way, and
>>>> with the removal of most of the hardware probing logic it
>>>> became clear that it was possible to simplify the logic a bit.
>>>>
>>>> This patch combines the walk of the DT nodes with the
>>>> code updating the cache size/line_size and nr_sets.
>>>> cache_override_properties() (which was DT specific) is
>>>> then removed. The result is that cacheinfo.of_node is
>>>> no longer used as a temporary place to hold DT references
>>>> for future calls that update cache properties. That change
>>>> helps to clarify its one remaining use (matching
>>>> cacheinfo nodes that represent shared caches) which
>>>> will be used by the ACPI/PPTT code in the following patches.
>>>>
>>>> Cc: Palmer Dabbelt <palmer@...ive.com>
>>>> Cc: Albert Ou <albert@...ive.com>
>>>> Signed-off-by: Jeremy Linton <jeremy.linton@....com>
>>>> ---
>>>>    arch/riscv/kernel/cacheinfo.c |  1 +
>>>>    drivers/base/cacheinfo.c      | 65
>>>> +++++++++++++++++++------------------------
>>>>    include/linux/cacheinfo.h     |  1 +
>>>>    3 files changed, 31 insertions(+), 36 deletions(-)
>>>>
>>>> diff --git a/arch/riscv/kernel/cacheinfo.c
>>>> b/arch/riscv/kernel/cacheinfo.c
>>>> index 10ed2749e246..6f4500233cf8 100644
>>>> --- a/arch/riscv/kernel/cacheinfo.c
>>>> +++ b/arch/riscv/kernel/cacheinfo.c
>>>> @@ -30,6 +30,7 @@ static void ci_leaf_init(struct cacheinfo *this_leaf,
>>>>            CACHE_WRITE_BACK
>>>>            | CACHE_READ_ALLOCATE
>>>>            | CACHE_WRITE_ALLOCATE;
>>>> +    cache_of_set_props(this_leaf, node);
>>>
>>> This may be necessary but can it be done as later patch ? So far nothing
>>> is added that may break riscv IIUC.
>>
>> Well I think you have a bisection issue where the additional information
>> will disappear between this patch and wherever we put this code back in.
>>
> 
> Hmm, I am sorry but I fail to see the issue. Before this change,
> populate_cache_leaves just populated the info as per ci_leaf_init in
> arch/riscv/kernel/cacheinfo.c and cache_override_properties used to fill
> the remaining.
> 
> After this patch, the same is achieved in cache_shared_cpu_map_setup.
> 
> In both case, it was by the end of detect_cache_attributes, so I see no
> issue.
> 


Hi,

I must be misunderstanding something.

AFAIK, The code in cache_setup_of_node() won't call cache_of_set_props() 
because it returns when there is an existing of_node (fw_unique) created 
by the riscv populate_cache_leaves(). That's why I'm making the direct 
call here. If we fail to get that change in place before 
cache_override_properties() is removed then the fields not set by the 
riscv code (size/etc) will be missing.