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 23/33] ARM: dts: exynos: Remove empty camera pinctrl
 configuration in Odroid X/U3
To:     Krzysztof Kozlowski <krzk@kernel.org>
Cc:     Sylwester Nawrocki <snawrocki@kernel.org>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Rob Herring <robh+dt@kernel.org>,
        Kukjin Kim <kgene@kernel.org>, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        "linux-samsung-soc@vger.kernel.org" 
        <linux-samsung-soc@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Denis GNUtoo Carikli <GNUtoo@cyberdimension.org>,
        Simon Shields <simon@lineageos.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
From:   Sylwester Nawrocki <s.nawrocki@samsung.com>
Message-ID: <01bb90db-511d-fbf5-d29a-1fba932f0abf@samsung.com>
Date:   Mon, 31 Aug 2020 15:57:08 +0200
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101
        Thunderbird/68.11.0
MIME-Version: 1.0
In-Reply-To: <CAJKOXPdF4zzXvYrOiGQM9o=4rrWHvEr=o9aSTuR238dEaiD4cQ@mail.gmail.com>
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Content-Type: text/plain; charset="utf-8"
CMS-TYPE: 201P
References: <20200830135200.24304-1-krzk@kernel.org>
        <CGME20200830135508eucas1p21ad0d4f6a2ef78f854fc74750db3fa2a@eucas1p2.samsung.com>
        <20200830135200.24304-23-krzk@kernel.org>
        <c9daff05-dca7-f1b1-8cfe-46b185bf60dd@samsung.com>
        <CAJKOXPfR8YVmBqCd5+8B2TdM_tXZbWobK0pLxXxxkrsDEMR-vw@mail.gmail.com>
        <96651e85-c27f-3167-7b41-2ea051c25c65@kernel.org>
        <CAJKOXPdF4zzXvYrOiGQM9o=4rrWHvEr=o9aSTuR238dEaiD4cQ@mail.gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 31.08.2020 12:42, Krzysztof Kozlowski wrote:
> On Mon, 31 Aug 2020 at 12:35, Sylwester Nawrocki <snawrocki@kernel.org> wrote:
>> On 8/31/20 10:38, Krzysztof Kozlowski wrote:
>>> On Mon, 31 Aug 2020 at 10:31, Marek Szyprowski <m.szyprowski@samsung.com> wrote:
>>>> On 30.08.2020 15:51, Krzysztof Kozlowski wrote:
>>>>> The camera's pinctrl configuration is simply empty and not effective.
>>>>> Remove it to fix dtbs_check warning:
>>>>>
>>>>>     arch/arm/boot/dts/exynos4412-odroidx.dt.yaml: camera: pinctrl-0: True is not of type 'array'
>>>>>
>>>>> Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
>>>>
>>>> I think that this was intentional to properly enable support for
>>>> mem-2-mem mode in Exynos4-IS (FIMC), but I'm not sure what are the
>>>> default values if no pinctrl properties are provided. Sylwester, could
>>>> you comment?
>>>
>>> Indeed it could be intentional... I see now errors:
>>> [   33.752203] s5p-fimc-md soc:camera: Failed to get pinctrl: -19
>>>
>>> I wonder why getting an empty pinctrl is needed... maybe the driver
>>> should accept missing pinctrl?
>>
>> It might have been better to have the pinctrl properties optional, as there
>> might be boards without the image sensor attached and FIMC could still be
>> used in memory-to-memory mode, as Marek pointed out. But it seems too late
>> now to change that. The binding defines the pinctrl properties as required
>> (Documentation/devicetree/bindings/media/samsung-fimc.txt) and we need to
>> keep them in dtses.
> 
> You can always make a required property optional and it is not a break
> of ABI. The other way around would be a break. Why then not changing
> the driver to accept optional pinctrl?

Feel free to send the patch, I would prefer to leave that as is though.
Is it really suddenly a problem to use an empty property? The pinctrl 
bindings allows it.

-- 
Regards,
Sylwester