linux-kernel - Re: [PATCH 2/2] ARM: dts: exynos: Remove interrupts from DMC controller in Exynos5422

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Message-ID: <2099aea9-5a63-6e5b-d7f9-4e6476584461@arm.com>
Date:   Mon, 17 Aug 2020 18:17:06 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, willy.mh.wolff.ml@...il.com,
        k.konieczny@...sung.com, cw00.choi@...sung.com,
        b.zolnierkie@...sung.com, chanwoo@...nel.org,
        myungjoo.ham@...sung.com, kyungmin.park@...sung.com,
        s.nawrocki@...sung.com, kgene@...nel.org
Subject: Re: [PATCH 2/2] ARM: dts: exynos: Remove interrupts from DMC
 controller in Exynos5422

Hi Krzysztof,

On 8/17/20 4:50 PM, Krzysztof Kozlowski wrote:
> On Wed, Jul 08, 2020 at 04:34:20PM +0100, Lukasz Luba wrote:
>> The interrupts in Dynamic Memory Controller in Exynos5422 and Odroid
>> XU3-family boards are no longer needed. They have been used in order
>> to workaround some issues in scheduled work in devfreq. Now when the
>> devfreq framework design is improved, remove the interrupt driven
>> approach and rely on devfreq monitoring mechanism with fixed intervals.
>>
>> Reported-by: Willy Wolff <willy.mh.wolff.ml@...il.com>
>> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
>> ---
>>   arch/arm/boot/dts/exynos5420.dtsi | 3 ---
>>   1 file changed, 3 deletions(-)
> 
> I think the dependencies were merged so this can be safely applied
> without bisectability problems?

I have created v2 of that fix and it got merged
via Chanwoo's tree, the commit 4fc9a0470d2dc37028
https://lkml.org/lkml/2020/7/10/1048

That commit switched the driver default mode from 'irq driven' to
new devfreq monitoring mechanism. Furthermore, when the driver is
built as a module, you can try to use the 'irq mode', but for this
you would need the DT IRQs description (this $subject tries to remove).

I would like to keep this IRQ mode for experimentation, as I
described in answers to Bartek's questions:
https://lkml.org/lkml/2020/7/14/315

Unfortunately, I am quite busy and won't make any progress before the
LPC.

Regards,
Lukasz