Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH] drm/exynos: add CONFIG_MMU dependency
To:     Arnd Bergmann <arnd@arndb.de>, Inki Dae <inki.dae@samsung.com>,
        Joonyoung Shim <jy0922.shim@samsung.com>,
        Seung-Woo Kim <sw0312.kim@samsung.com>,
        Kyungmin Park <kyungmin.park@samsung.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>, Kukjin Kim <kgene@kernel.org>,
        Krzysztof Kozlowski <krzk@kernel.org>
Cc:     linux-samsung-soc@vger.kernel.org,
        Jingoo Han <jingoohan1@gmail.com>,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        Andrzej Hajda <a.hajda@samsung.com>,
        Sam Ravnborg <sam@ravnborg.org>,
        linux-arm-kernel@lists.infradead.org
References: <20190708134707.538501-1-arnd@arndb.de>
From:   Vladimir Murzin <vladimir.murzin@arm.com>
Message-ID: <ea185bd7-3ac7-dc38-1c0e-78cb1cffa6a0@arm.com>
Date:   Mon, 8 Jul 2019 15:09:04 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.7.0
MIME-Version: 1.0
In-Reply-To: <20190708134707.538501-1-arnd@arndb.de>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 7/8/19 2:46 PM, Arnd Bergmann wrote:
> Compile-testing this driver on a NOMMU configuration shows a link failure:
> 
> drivers/gpu/drm/exynos/exynos_drm_gem.o: In function `exynos_drm_gem_fault':
> exynos_drm_gem.c:(.text+0x484): undefined reference to `vmf_insert_mixed'
> 
> Add a CONFIG_MMU dependency to ensure we only enable this in configurations
> that build correctly.
> 
> Many other drm drivers have the same dependency. It would be nice to
> make this work in MMU-less configurations, but evidently nobody has
> ever needed this so far.
> 
> Fixes: 156bdac99061 ("drm/exynos: trigger build of all modules")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/gpu/drm/exynos/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/exynos/Kconfig b/drivers/gpu/drm/exynos/Kconfig
> index 60ce4a8ad9e1..6f7d3b3b3628 100644
> --- a/drivers/gpu/drm/exynos/Kconfig
> +++ b/drivers/gpu/drm/exynos/Kconfig
> @@ -2,6 +2,7 @@
>  config DRM_EXYNOS
>  	tristate "DRM Support for Samsung SoC EXYNOS Series"
>  	depends on OF && DRM && (ARCH_S3C64XX || ARCH_S5PV210 || ARCH_EXYNOS || ARCH_MULTIPLATFORM || COMPILE_TEST)
> +	depends on MMU
>  	select DRM_KMS_HELPER
>  	select VIDEOMODE_HELPERS
>  	select SND_SOC_HDMI_CODEC if SND_SOC
> 

I seen

ERROR: "vmf_insert_mixed" [drivers/gpu/drm/exynos/exynosdrm.ko] undefined!

with older kernels when driver was build as a module, so FWIW

Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>

Cheers
Vladimir