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

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Message-ID: <mhng-758d7724-dc4c-4d08-adf2-967862df2925@palmer-si-x1c4>
Date:   Thu, 18 Jan 2018 09:36:42 -0800 (PST)
From:   Palmer Dabbelt <palmer@...ive.com>
To:     sudeep.holla@....com
CC:     sudeep.holla@....com, jeremy.linton@....com,
        linux-acpi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        hanjun.guo@...aro.org, lorenzo.pieralisi@....com,
        rjw@...ysocki.net, Will Deacon <will.deacon@....com>,
        catalin.marinas@....com, Greg KH <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,
        albert@...ive.com
Subject:     Re: [PATCH v6 02/12] drivers: base: cacheinfo: setup DT cache properties early

On Wed, 17 Jan 2018 10:08:27 PST (-0800), sudeep.holla@....com wrote:
> (Sorry, somehow I missed this email until I saw Jeremy's reply today)
>
> On 15/01/18 16:07, Palmer Dabbelt wrote:
>> On Mon, 15 Jan 2018 04:33:38 PST (-0800), sudeep.holla@....com 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.
>>>
>>> Palmer, Albert,
>>>
>>> Can you confirm ? Also, as I see we can thin down arch specific
>>> implementation on riscv if it's just using DT like ARM64. Sorry if
>>> I am missing to see something, so thought of checking.
>>>
>>> [...]
>>
>> Sorry, I guess I'm a bit confused as to what's going on here.  RISC-V
>> uses device tree on all Linux systems.
>>
>
> Good. By thin down, I was thinking of moving the init_cache_level and
> populate_cache_leaves implementation of riscv to generic weak function
> under CONFIG_OF. You may even endup deleting riscv cacheinfo.c
>
> Just a thought, sorry for not being clear earlier.

OK, well, I'm always happy to convert things to generic implementations.