Re: [PATCH v3 00/13] drm/display: Convert helpers Kconfig symbols to depends on

From: Diederik de Haas <didi.debian@cknow.org>
To: Maxime Ripard <mripard@kernel.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>,
	Jani Nikula <jani.nikula@linux.intel.com>,
	dri-devel@lists.freedesktop.org,
	Jani Nikula <jani.nikula@intel.com>,
	Lucas De Marchi <lucas.demarchi@intel.com>,
	kernel test robot <lkp@intel.com>,
	linux-renesas-soc@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 00/13] drm/display: Convert helpers Kconfig symbols to depends on
Date: Wed, 10 Apr 2024 21:46:54 +0200	[thread overview]
Message-ID: <3688196.Heb4DZiL54@bagend> (raw)
In-Reply-To: <a816fea-9974-d17f-bed6-69728e223@linux-m68k.org>

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On Tuesday, 9 April 2024 11:26:25 CEST Geert Uytterhoeven wrote:
>  	Hi Maxime,
> 
> On Wed, 27 Mar 2024, Maxime Ripard wrote:
> > Jani recently pointed out that the Kconfig symbols are a bit difficult
> > to work with at the moment when they depend on each other, and that
> > using depends on would be a better idea, but no one really did the work
> > so far.
> > 
> > So here it goes :)
> > 
> > It's been tested by comparing the riscv defconfig, arm
> > multi_v7_defconfig, arm64 defconfig, drm-misc-arm, drm-misc-arm64 and
> > drm-misc-x86 before and after this series and making sure they are
> > identical.
> 
> That is not true: comparing drm-misc/for-linux-next to v6.9-rc2,
> arm/multi_v7_defconfig, arm64/defconfig, and riscv/defconfig lost
> several of:
>    - CONFIG_DRM_DW_HDMI,
>    - CONFIG_DRM_DW_HDMI_AHB_AUDIO,
>    - CONFIG_DRM_DW_HDMI_CEC,
>    - CONFIG_DRM_DW_HDMI_I2S_AUDIO,
>    - CONFIG_DRM_IMX_HDMI.
>    - CONFIG_DRM_MESON_DW_HDMI,
>    - CONFIG_DRM_RCAR_DW_HDMI,
>    - CONFIG_DRM_SUN8I_DW_HDMI,
>    - CONFIG_ROCKCHIP_DW_HDMI,
>    - CONFIG_SND_MESON_G12A_TOHDMITX,
> 
> > Let me know what you think,
> 
> IMHO this series looks like a big usuability issue for anyone
> configuring the kernel, and you try to work around this by sprinkling
> "default y" around.
> 
> The user should not need to know which helpers are needed for the driver
> he is interested in.  When a symbol selects another symbol, it should
> just make sure the dependencies of the target symbol are met.
> 
> Thanks for reverting ;-)

I *think* that I ran into this issue (but it may also be KEBKAC).
I tried to build a Debian arm64 kernel from 6.9-rc3 with a number of drm-misc-
next patches, including this patch set.

debian/config/arm64/config: CONFIG_DRM_SUN8I_DW_HDMI=m

In my 6.7.9 kernel the sun8i-drm-hdmi module got build.
(as well as meson_dw_hdmi, although it does not have an explicit configuration 
for it, but there appears a similarity with it in the `drm: Make drivers 
depends on DRM_DW_HDMI` commit)

But in my newly build kernel both are NOT build.
While I can't complain about meson_dw_hdmi, I would have expected the sun8i-
drm-hdmi module to be build.

Cheers,
  Diederik

PS: The Kconfig says that the module will be called `sun8i_dw_hdmi`, but that 
seems to be incorrect

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