Re: [RFC PATCH 0/2] DRM driver for hyper-v synthetic video device

From: Daniel Vetter <daniel@ffwll.ch>
To: Deepak Rawat <drawat.floss@gmail.com>
Cc: linux-hyperv@vger.kernel.org,
	dri-devel <dri-devel@lists.freedesktop.org>,
	David Airlie <airlied@linux.ie>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	K Y Srinivasan <kys@microsoft.com>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	Wei Liu <wei.liu@kernel.org>, Wei Hu <weh@microsoft.com>,
	Jork Loeser <jloeser@microsoft.com>,
	Michael Kelley <mikelley@microsoft.com>
Subject: Re: [RFC PATCH 0/2] DRM driver for hyper-v synthetic video device
Date: Mon, 29 Jun 2020 01:01:52 +0200	[thread overview]
Message-ID: <CAKMK7uExRNRV8spaBzaO8syPiFGw-8f5ZHLhtZj159JsRFMRPw@mail.gmail.com> (raw)
In-Reply-To: <20200622110623.113546-1-drawat.floss@gmail.com>

On Mon, Jun 22, 2020 at 1:07 PM Deepak Rawat <drawat.floss@gmail.com> wrote:
>
> Hi All,
>
> First draft of DRM driver for hyper-v synthetic video device. This synthetic
> device is already supported by hyper-v and a corresponding framebuffer driver
> exist at drivers/video/fbdev/hyperv_fb.c. With this patch, just reworked the
> framebuffer driver into DRM, in doing so got mode-setting support. The code is
> similar to cirrus DRM driver, using simple display pipe and shmem backed
> GEM objects.
>
> The device support more features like hardware cursor, EDID, multiple dirty
> regions, etc, which were not supported with framebuffer driver. The plan is to
> add support for those in future iteration. Wanted to get initial feedback and
> discuss cursor support with simple kms helper. Is there any value to add cursor
> support to drm_simple_kms_helper.c so that others can use it, or should I just
> add cursor plane as device private? I believe we can still keep this driver
> in drm/tiny?

Simple is for really simple framebuffers, if you want a few planes or
multiple outputs or multiple crtcs then just write a normal drm
driver. We've worked hard to ditch all the boilerplate and replace it
with defaults, so the difference isn't much, and if we don't keep
simple helpers really simple there's not much point.

Also once you don't use simple helpers anymore I think migrating out
of drm/tiny is probably a good idea.
-Daniel

> For testing, ran GNOME and Weston with current changes in a Linux VM on
> Windows 10 with hyper-v enabled.
>
> Thanks,
> Deepak
>
> Deepak Rawat (2):
>   drm/hyperv: Add DRM driver for hyperv synthetic video device
>   MAINTAINERS: Add maintainer for hyperv video device
>
>  MAINTAINERS                       |    8 +
>  drivers/gpu/drm/tiny/Kconfig      |    9 +
>  drivers/gpu/drm/tiny/Makefile     |    1 +
>  drivers/gpu/drm/tiny/hyperv_drm.c | 1007 +++++++++++++++++++++++++++++
>  4 files changed, 1025 insertions(+)
>  create mode 100644 drivers/gpu/drm/tiny/hyperv_drm.c
>
> --
> 2.27.0
>

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch