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Date:   Thu, 27 Jan 2022 11:05:28 +0200
From:   Pekka Paalanen <ppaalanen@gmail.com>
To:     Javier Martinez Canillas <javierm@redhat.com>
Cc:     linux-kernel@vger.kernel.org,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Jonathan Corbet <corbet@lwn.net>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        dri-devel@lists.freedesktop.org, linux-doc@vger.kernel.org,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Subject: Re: [PATCH] drm/doc: Add section in the introduction page about
 learning material
Message-ID: <20220127110528.20604049@eldfell>
In-Reply-To: <20220127082058.434421-1-javierm@redhat.com>
References: <20220127082058.434421-1-javierm@redhat.com>
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On Thu, 27 Jan 2022 09:20:58 +0100
Javier Martinez Canillas <javierm@redhat.com> wrote:

> The Linux DRM subsystem supports complex graphics devices and it could be
> quite overwhelming for newcomers to learn about the subsystem's internals.
>=20
> There are lots of useful talks, slides and articles available that can be
> used to get familiar with the needed concepts and ease the learning curve.
>=20
> Add a section to the intro that contains these DRM introductory materials.
>=20
> Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
> ---
>=20
>  Documentation/gpu/introduction.rst | 36 ++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
>=20
> diff --git a/Documentation/gpu/introduction.rst b/Documentation/gpu/intro=
duction.rst
> index 25a56e9c0cfd..35986784f916 100644
> --- a/Documentation/gpu/introduction.rst
> +++ b/Documentation/gpu/introduction.rst
> @@ -112,3 +112,39 @@ Please conduct yourself in a respectful and civilise=
d manner when
>  interacting with community members on mailing lists, IRC, or bug
>  trackers. The community represents the project as a whole, and abusive
>  or bullying behaviour is not tolerated by the project.
> +
> +Learning material
> +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> +
> +Since the Linux DRM layer supports complex graphics devices, it can be q=
uite
> +overwhelming for newcomers to get familiar with all the needed concepts =
and
> +learn the subsystem's internals.

Hi,

this seems to say that DRM is going to be complicated no matter what
hardware one wants to drive, but is that true?

Is there no way to say that if your display hardware is simple (no
GPU), then the driver can be simple to write too?

> +
> +To shallow the learning curve, this section contains a list of presentat=
ions
> +and documents that can be used to learn about DRM/KMS and graphics in ge=
neral.
> +
> +The list is sorted in reverse chronological order, to keep the most up-t=
o-date
> +material at the top. But all of them contain useful information, and it =
can be
> +valuable to go through older material to understand the rationale and co=
ntext
> +in which the recent changes to the DRM subsystem were made.
> +
> +Talks
> +-----
> +
> +* `An Overview of the Linux and Userspace Graphics Stack <https://www.yo=
utube.com/watch?v=3DwjAJmqwg47k>`_ - Paul Kocialkowski (2020)
> +* `Getting pixels on screen on Linux: introduction to Kernel Mode Settin=
g <https://www.youtube.com/watch?v=3Dhaes4_Xnc5Q>`_ - Simon Ser (2020)
> +* `An introduction to the Linux DRM subsystem <https://www.youtube.com/w=
atch?v=3DLbDOCJcDRoo>`_ - Maxime Ripard (2017)
> +* `Embrace the Atomic (Display) Age <https://www.youtube.com/watch?v=3DL=
jiB_JeDn2M>`_ - Daniel Vetter (2016)
> +* `Anatomy of an Atomic KMS Driver <https://www.youtube.com/watch?v=3Dli=
hqR9sENpc>`_ - Laurent Pinchart (2015)
> +* `Atomic Modesetting for Drivers <https://www.youtube.com/watch?v=3Dkl9=
suFgbTc8>`_ - Daniel Vetter (2015)
> +* `Anatomy of an Embedded KMS Driver <https://www.youtube.com/watch?v=3D=
Ja8fM7rTae4>`_ - Laurent Pinchart (2013
> +
> +Slides and articles
> +-------------------
> +
> +* `Understanding the Linux Graphics Stack <https://bootlin.com/doc/train=
ing/graphics/graphics-slides.pdf>`_ - Bootlin (2022)
> +* `DRM KMS overview <https://wiki.st.com/stm32mpu/wiki/DRM_KMS_overview>=
`_ - STMicroelectronics (2021)
> +* `Linux graphic stack <https://studiopixl.com/2017-05-13/linux-graphic-=
stack-an-overview>`_ - Nathan Gau=C3=ABr (2017)
> +* `The DRM/KMS subsystem from a newbie=E2=80=99s point of view <https://=
bootlin.com/pub/conferences/2014/elce/brezillon-drm-kms/brezillon-drm-kms.p=
df>`_ - Boris Brezillon (2014)
> +* `A brief introduction to the Linux graphics stack <https://blogs.igali=
a.com/itoral/2014/07/29/a-brief-introduction-to-the-linux-graphics-stack/>`=
_ - Iago Toral (2014)
> +* `The Linux Graphics Stack <https://blog.mecheye.net/2012/06/the-linux-=
graphics-stack/>`_ - Jasper St. Pierre (2012)

That's an impressive list of links!

However, given the discussions that prompted this doc, I think the gist
is missing. The reader is just flooded with stuff to read and learn
which can be discouraging.

Your audience are developers who know nothing about DRM. They may have
been writing fb drivers instead. The display hardware they want to
drive has no GPU. Where should they get started? Which presentations to
read/watch first? Which driver to look at for a simple example?

Maybe add one more section targeting that specific audience?


Thanks,
pq

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