linux-kernel - Re: [PATCH 1/2] memory: samsung: exynos5422-dmc: Adjust polling interval and uptreshold

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Date:   Fri, 10 Jul 2020 15:13:18 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Lukasz Luba <lukasz.luba@....com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org
Cc:     willy.mh.wolff.ml@...il.com, k.konieczny@...sung.com,
        b.zolnierkie@...sung.com, krzk@...nel.org, chanwoo@...nel.org,
        myungjoo.ham@...sung.com, kyungmin.park@...sung.com,
        s.nawrocki@...sung.com, kgene@...nel.org
Subject: Re: [PATCH 1/2] memory: samsung: exynos5422-dmc: Adjust polling
 interval and uptreshold

Hi Lukasz,

On 10.07.2020 10:34, Lukasz Luba wrote:
> Hi Chanwoo,
>
> On 7/9/20 5:08 AM, Chanwoo Choi wrote:
>> Hi Lukasz,
>>
>> On 7/9/20 12:34 AM, Lukasz Luba wrote:
>>> In order to react faster and make better decisions under some 
>>> workloads,
>>> benchmarking the memory subsystem behavior, adjust the polling interval
>>> and upthreshold value used by the simple_ondemand governor.
>>>
>>> Reported-by: Willy Wolff <willy.mh.wolff.ml@...il.com>
>>> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
>>> ---
>>>   drivers/memory/samsung/exynos5422-dmc.c | 4 ++--
>>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/memory/samsung/exynos5422-dmc.c 
>>> b/drivers/memory/samsung/exynos5422-dmc.c
>>> index 93e9c2429c0d..e03ee35f0ab5 100644
>>> --- a/drivers/memory/samsung/exynos5422-dmc.c
>>> +++ b/drivers/memory/samsung/exynos5422-dmc.c
>>> @@ -1466,10 +1466,10 @@ static int exynos5_dmc_probe(struct 
>>> platform_device *pdev)
>>>            * Setup default thresholds for the devfreq governor.
>>>            * The values are chosen based on experiments.
>>>            */
>>> -        dmc->gov_data.upthreshold = 30;
>>> +        dmc->gov_data.upthreshold = 10;
>>>           dmc->gov_data.downdifferential = 5;
>>>   -        exynos5_dmc_df_profile.polling_ms = 500;
>>> +        exynos5_dmc_df_profile.polling_ms = 100;
>>>       }
>>>
>>
>> Reviewed-by: Chanwoo Choi <cw00.choi@...sung.com>
>>
>
> Thank you for the review. Do you think this patch could go through
> your tree together with your patches?
>
> I don't know Krzysztof's opinion about the patch 2/2, but
> I would expect, assuming the patch itself is correct, he would
> like to take it into his next/dt branch.

Is there really a need to remove the interrupts property? imho they are 
correct hw description, it just a matter of the driver to use or not to 
use them.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland