Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH v2 2/2] memory: samsung: exynos5422-dmc: Add module
 param to control IRQ mode
To:     Lukasz Luba <lukasz.luba@arm.com>, linux-kernel@vger.kernel.org,
        linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-samsung-soc@vger.kernel.org
Cc:     willy.mh.wolff.ml@gmail.com, k.konieczny@samsung.com,
        cw00.choi@samsung.com, b.zolnierkie@samsung.com, krzk@kernel.org,
        chanwoo@kernel.org, myungjoo.ham@samsung.com,
        kyungmin.park@samsung.com, s.nawrocki@samsung.com, kgene@kernel.org
From:   Marek Szyprowski <m.szyprowski@samsung.com>
Message-ID: <db571467-48ec-8f11-de1d-00393d8aa99b@samsung.com>
Date:   Mon, 3 Aug 2020 17:30:30 +0200
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101
        Thunderbird/68.10.0
MIME-Version: 1.0
In-Reply-To: <20200710191122.11029-3-lukasz.luba@arm.com>
Content-Transfer-Encoding: 8bit
Content-Language: en-US
Content-Type: text/plain; charset="utf-8"
CMS-TYPE: 201P
References: <20200710191122.11029-1-lukasz.luba@arm.com>
        <CGME20200710191154eucas1p296561f285ee0730e5040fdfe3fc7e75e@eucas1p2.samsung.com>
        <20200710191122.11029-3-lukasz.luba@arm.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Lukasz,

On 10.07.2020 21:11, Lukasz Luba wrote:
> The driver can operate in two modes relaying on devfreq monitoring
> mechanism which periodically checks the device status or it can use
> interrupts when they are provided by loaded Device Tree. The newly
> introduced module parameter can be used to choose between devfreq
> monitoring and internal interrupts without modifying the Device Tree.
> It also sets devfreq monitoring as default when the parameter is not set
> (also the case for default when the driver is not built as a module).
>
> Reported-by: Willy Wolff <willy.mh.wolff.ml@gmail.com>
> Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>

I've got back from my holidays and noticed that in meantime this commit 
got merged as commit 4fc9a0470d2d. It revealed that there is a race 
between registering exynos5422-dmc driver and exynos-ppmu driver, which 
can be observed sometimes as the following message and freeze on Odroid 
XU3 with multi_v7_defconfig:

[    8.767708] exynos5-dmc 10c20000.memory-controller: couldn't probe 
performance counters

I will check this later why the EPROBE_DEFER error is not properly 
propagated and why it causes a freeze.

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