linux-kernel - Re: [v10,20/27] drm/connector: hdmi: Add Infoframes generation

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Date: Fri, 22 Mar 2024 13:46:42 +0200
From: Jani Nikula <jani.nikula@...ux.intel.com>
To: Maxime Ripard <mripard@...nel.org>
Cc: Sui Jingfeng <sui.jingfeng@...ux.dev>, Maarten Lankhorst
 <maarten.lankhorst@...ux.intel.com>, Thomas Zimmermann
 <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Daniel Vetter
 <daniel@...ll.ch>, Jonathan Corbet <corbet@....net>, Sandy Huang
 <hjc@...k-chips.com>, Heiko Stübner <heiko@...ech.de>,
 Chen-Yu Tsai
 <wens@...e.org>, Jernej Skrabec <jernej.skrabec@...il.com>, Samuel Holland
 <samuel@...lland.org>, Hans Verkuil <hverkuil@...all.nl>, Sebastian Wick
 <sebastian.wick@...hat.com>, Ville Syrjälä
 <ville.syrjala@...ux.intel.com>, dri-devel@...ts.freedesktop.org,
 linux-arm-kernel@...ts.infradead.org, linux-doc@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
 linux-rockchip@...ts.infradead.org, linux-sunxi@...ts.linux.dev
Subject: Re: [v10,20/27] drm/connector: hdmi: Add Infoframes generation

On Fri, 22 Mar 2024, Maxime Ripard <mripard@...nel.org> wrote:
> On Fri, Mar 22, 2024 at 11:22:14AM +0200, Jani Nikula wrote:
>> On Fri, 22 Mar 2024, Sui Jingfeng <sui.jingfeng@...ux.dev> wrote:
>> > Hi,
>> >
>> >
>> > On 2024/3/21 23:29, Maxime Ripard wrote:
>> >> Infoframes in KMS is usually handled by a bunch of low-level helpers
>> >> that require quite some boilerplate for drivers. This leads to
>> >> discrepancies with how drivers generate them, and which are actually
>> >> sent.
>> >>
>> >> Now that we have everything needed to generate them in the HDMI
>> >> connector state, we can generate them in our common logic so that
>> >> drivers can simply reuse what we precomputed.
>> >>
>> >> Signed-off-by: Maxime Ripard <mripard@...nel.org>
>> >> ---
>> >>   drivers/gpu/drm/Kconfig                            |   1 +
>> >>   drivers/gpu/drm/drm_atomic_state_helper.c          | 338 +++++++++++++++++++++
>> >>   drivers/gpu/drm/drm_connector.c                    |  14 +
>> >>   .../gpu/drm/tests/drm_atomic_state_helper_test.c   |   1 +
>> >>   drivers/gpu/drm/tests/drm_connector_test.c         |  12 +
>> >>   include/drm/drm_atomic_state_helper.h              |   8 +
>> >>   include/drm/drm_connector.h                        | 109 +++++++
>> >>   7 files changed, 483 insertions(+)
>> >>
>> >> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
>> >> index 16029435b750..3d3193c7aa5f 100644
>> >> --- a/drivers/gpu/drm/Kconfig
>> >> +++ b/drivers/gpu/drm/Kconfig
>> >> @@ -97,10 +97,11 @@ config DRM_KUNIT_TEST
>> >>   	  If in doubt, say "N".
>> >>   
>> >>   config DRM_KMS_HELPER
>> >>   	tristate
>> >>   	depends on DRM
>> >> +	select DRM_DISPLAY_HDMI_HELPER
>> >
>> > Should we select DRM_DISPLAY_HELPER here? Otherwise there will have some compile error
>> > emerged with default config.
>> 
>> Can we stop abusing select instead of adding more selects to paper over
>> the issues?
>> 
>> Use select only for non-visible symbols (no prompts anywhere) and for
>> symbols with no dependencies.
>
> I don't really have an opinion there, but it looks like all the other
> helpers Kconfig symbols are using select everywhere, and I don't really
> see how we could turn them into visible symbols with depends on without
> breaking a number of defconfig.
>
> Could you expand a bit what you have in mind here?

Just my standard grumbling about the rampant select abuse.

Maybe one day someone takes the hint and starts fixing things up. :p

See the note under "reverse dependencies" at [1].


BR,
Jani.


[1] https://docs.kernel.org/kbuild/kconfig-language.html#menu-attributes


-- 
Jani Nikula, Intel