Re: [PATCH v5 00/19] R-Car DU display writeback support

From: Brian Starkey <Brian.Starkey@arm.com>
To: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Cc: Liviu Dudau <Liviu.Dudau@arm.com>, nd <nd@arm.com>,
	"james qian wang (Arm Technology China)"
	<james.qian.wang@arm.com>,
	Kieran Bingham <kieran.bingham@ideasonboard.com>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH v5 00/19] R-Car DU display writeback support
Date: Fri, 22 Feb 2019 14:04:10 +0000	[thread overview]
Message-ID: <20190222140411.wlpe2pdmdzh7fjqr@DESKTOP-E1NTVVP.localdomain> (raw)
In-Reply-To: <20190221103212.28764-1-laurent.pinchart+renesas@ideasonboard.com>

Hi,

On Thu, Feb 21, 2019 at 12:31:53PM +0200, Laurent Pinchart wrote:
> Hello everybody,
> 
> This patch series implements display writeback support for the R-Car
> Gen3 platforms in the VSP1 and DU drivers.
> 
> Patches 01/19 to 11/19 prepare the VSP1 driver for writeback support
> with all the necessary plumbing, including extensions of the API between
> the VSP1 and DU drivers.
> 
> Compared to v4 the major change is the move from V4L2 to DRM writeback
> connectors for the userspace API. This has caused a few issues with
> writeback support to be uncovered, and they are addressed by patches
> 12/19 to 14/19. Patch 15/19 is an unrelated drive-by fix.
> 
> Patches 16/19 to 18/19 then perform refactoring of the DU driver, to
> finally add writeback support in patch 19/19.
> 
> The writeback pixel format is restricted to RGB, due to the VSP1
> outputting RGB to the display and lacking a separate colour space
> conversion unit for writeback. The resolution can be freely picked by
> will result in cropping or composing, not scaling.

I think this sentence about cropping doesn't match the implementation,
as you're checking the framebuffer size against the mode.

We want to enable scaling/composing on writeback (which our HW can
do). I thought we'd add WRITEBACK_X/Y/W/H properties to set the
destination buffer coordinates. One of our team is working on that
now.

We don't have cropping, but I thought that could be achieved by
exposing CRTC_X/Y/W/H on writeback connectors.

Thanks,
-Brian

> 
> Writeback requests are queued to the hardware on page flip (atomic
> flush), and complete at the next vblank. This means that a queued
> writeback buffer will not be processed until the next page flip, but
> once it starts being written to by the VSP, it will complete at the next
> vblank regardless of whether another page flip occurs at that time.
> 
> The code is based on a merge of the media master branch, the drm-next
> branch and the R-Car DT next branch. For convenience patches can be
> found at
> 
>         git://linuxtv.org/pinchartl/media.git v4l2/vsp1/writeback
> 
> Kieran Bingham (1):
>   Revert "[media] v4l: vsp1: Supply frames to the DU continuously"
> 
> Laurent Pinchart (18):
>   media: vsp1: wpf: Fix partition configuration for display pipelines
>   media: vsp1: Replace leftover occurrence of fragment with body
>   media: vsp1: Fix addresses of display-related registers for VSP-DL
>   media: vsp1: Refactor vsp1_video_complete_buffer() for later reuse
>   media: vsp1: Replace the display list internal flag with a flags field
>   media: vsp1: dl: Support one-shot entries in the display list
>   media: vsp1: wpf: Add writeback support
>   media: vsp1: drm: Split RPF format setting to separate function
>   media: vsp1: drm: Extend frame completion API to the DU driver
>   media: vsp1: drm: Implement writeback support
>   drm: writeback: Cleanup job ownership handling when queuing job
>   drm: writeback: Fix leak of writeback job
>   drm: writeback: Add job prepare and cleanup operations
>   drm/msm: Remove prototypes for non-existing functions
>   drm: rcar-du: Fix rcar_du_crtc structure documentation
>   drm: rcar-du: Store V4L2 fourcc in rcar_du_format_info structure
>   drm: rcar-du: vsp: Extract framebuffer (un)mapping to separate
>     functions
>   drm: rcar-du: Add writeback support for R-Car Gen3
> 
>  drivers/gpu/drm/arm/malidp_mw.c             |   3 +-
>  drivers/gpu/drm/drm_atomic_helper.c         |  11 ++
>  drivers/gpu/drm/drm_atomic_state_helper.c   |   4 +
>  drivers/gpu/drm/drm_atomic_uapi.c           |  31 +--
>  drivers/gpu/drm/drm_writeback.c             |  71 ++++++-
>  drivers/gpu/drm/msm/msm_drv.h               |   2 -
>  drivers/gpu/drm/rcar-du/Kconfig             |   4 +
>  drivers/gpu/drm/rcar-du/Makefile            |   3 +-
>  drivers/gpu/drm/rcar-du/rcar_du_crtc.h      |   9 +-
>  drivers/gpu/drm/rcar-du/rcar_du_kms.c       |  37 ++++
>  drivers/gpu/drm/rcar-du/rcar_du_kms.h       |   1 +
>  drivers/gpu/drm/rcar-du/rcar_du_vsp.c       | 121 ++++++------
>  drivers/gpu/drm/rcar-du/rcar_du_vsp.h       |  17 ++
>  drivers/gpu/drm/rcar-du/rcar_du_writeback.c | 203 ++++++++++++++++++++
>  drivers/gpu/drm/rcar-du/rcar_du_writeback.h |  39 ++++
>  drivers/gpu/drm/vc4/vc4_txp.c               |   2 +-
>  drivers/media/platform/vsp1/vsp1_dl.c       | 127 ++++++++++--
>  drivers/media/platform/vsp1/vsp1_dl.h       |   8 +-
>  drivers/media/platform/vsp1/vsp1_drm.c      |  92 ++++++---
>  drivers/media/platform/vsp1/vsp1_drm.h      |   2 +-
>  drivers/media/platform/vsp1/vsp1_drv.c      |  15 ++
>  drivers/media/platform/vsp1/vsp1_pipe.c     |   5 +
>  drivers/media/platform/vsp1/vsp1_pipe.h     |   1 +
>  drivers/media/platform/vsp1/vsp1_regs.h     |   6 +-
>  drivers/media/platform/vsp1/vsp1_rwpf.h     |   2 +
>  drivers/media/platform/vsp1/vsp1_video.c    |  49 +++--
>  drivers/media/platform/vsp1/vsp1_wpf.c      |  68 +++++--
>  include/drm/drm_modeset_helper_vtables.h    |   7 +
>  include/drm/drm_writeback.h                 |  30 ++-
>  include/media/vsp1.h                        |  19 +-
>  30 files changed, 790 insertions(+), 199 deletions(-)
>  create mode 100644 drivers/gpu/drm/rcar-du/rcar_du_writeback.c
>  create mode 100644 drivers/gpu/drm/rcar-du/rcar_du_writeback.h
> 
> -- 
> Regards,
> 
> Laurent Pinchart
> 
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