Message-ID: <6129743.3Euq8y3YuW@avalon>
Date:   Thu, 22 Feb 2018 12:25:08 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Frank Rowand <frowand.list@...il.com>
Cc:     Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
        dri-devel@...ts.freedesktop.org, linux-renesas-soc@...r.kernel.org,
        Rob Herring <robh@...nel.org>,
        Matt Porter <mporter@...sulko.com>,
        Koen Kooi <koen@...inion.thruhere.net>,
        Guenter Roeck <linux@...ck-us.net>,
        Marek Vasut <marex@...x.de>, Wolfram Sang <wsa@...-dreams.de>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-i2c@...r.kernel.org,
        Pantelis Antoniou <pantelis.antoniou@...sulko.com>
Subject: Re: [PATCH v4 00/16] R-Car DU: Convert LVDS code to bridge driver

Hi Frank,

On Thursday, 22 February 2018 08:07:14 EET Frank Rowand wrote:
> On 02/20/18 15:10, Laurent Pinchart wrote:
> > Hello,
> > 
> > This patch series addresses a design mistake that dates back from the
> > initial DU support. Support for the LVDS encoders, which are IP cores
> > separate from the DU, was bundled in the DU driver. Worse, both the DU
> > and LVDS were described through a single DT node.
> > 
> > To fix the, patches 01/16 and 02/16 define new DT bindings for the LVDS
> > encoders, and deprecate their description inside the DU bindings. To
> > retain backward compatibility with existing DT, patches 03/16 to 08/16
> > then patch the device tree at runtime to convert the legacy bindings to
> > the new ones.
> > 
> > With the DT side addressed, patch 09/16 converts the LVDS support code to
> > a separate bridge driver. Patches 11/16 to 16/16 then update all the
> > device tree sources to the new DU and LVDS encoders bindings.
> > 
> > I decided to go for live DT patching in patch 08/16 because implementing
> > support for both the legacy and new bindings in the driver would have been
> > very intrusive, and prevented further cleanups. This version relies more
> > heavily on overlays to avoid touching the internals of the OF core
> > compared to v2, even if manual fixes to the device tree are still needed.
> > 
> > Compared to v3, this series uses the OF changeset API to update properties
> > instead of accessing the internals of the property structure. This removes
> > the local implementation of functions to look up nodes by path and update
> > properties. In order to do this, I pulled in Pantelis' patch series
> > titled "[PATCH v2 0/5] of: dynamic: Changesets helpers & fixes" at Rob's
> > request, and rebased it while taking two small review comments into
> > account.
> 
> Wait a minute!  Why are you putting a patch set to modify core devicetree
> in the middle of a driver series.  Please pull it out to a separate series.

Because Rob asked for the driver-local implementation of the property add 
function to be replaced by Pantelis' series. I want to get the LVDS changes in 
v4.17 and asked Rob whether I could then take the OF changeset patches merged 
through the DRM tree, and he didn't object. If that causes an issue I'll 
switch back to the driver-local implementation to get the driver changes 
merged, split the OF changeset series out, and then move to the OF changeset 
API once merged. Would you prefer that ?

> I'll try to look at the patches, as they are in this series, sometime
> tomorrow.  I have a vague memory of unresolved issues from the last
> time they were proposed.
> 
> > Rob, I'd like this series to be merged in v4.17. As the changeset helpers
> > are now a dependency, I'd need you to merge them early (ideally on top of
> > v4.16-rc1) and provide a stable branch, or get your ack to merge them
> > through Dave's tree if they don't conflict with what you have and will
> > queue for v4.17.
> > 
> > This version also drops the small fix to the Porter board device tree that
> > has been queued for v4.17 already.
> > 
> > Compared to v2, the biggest change is in patch 03/16. Following Rob's and
> > Frank's reviews it was clear that modifying the unflattened DT structure
> > of the overlay before applying it wasn't popular. I have thus decided to
> > use one overlay source per SoC to move as much of the DT changes to the
> > overlay as possible, and only perform manual modifications (that are
> > still needed as some of the information is board-specific) on the system
> > DT after applying the overlay. As a result the overlay is parsed and
> > applied without being modified.
> > 
> > Compared to v1, this series update the r8a7792 and r8a7794 device tree
> > sources and incorporate review feedback as described by the changelogs of
> > individual patches.
> > 
> > Laurent Pinchart (11):
> >   dt-bindings: display: renesas: Add R-Car LVDS encoder DT bindings
> >   dt-bindings: display: renesas: Deprecate LVDS support in the DU
> >     bindings
> >   drm: rcar-du: Fix legacy DT to create LVDS encoder nodes
> >   drm: rcar-du: Convert LVDS encoder code to bridge driver
> >   ARM: dts: r8a7790: Convert to new LVDS DT bindings
> >   ARM: dts: r8a7791: Convert to new LVDS DT bindings
> >   ARM: dts: r8a7792: Convert to new DU DT bindings
> >   ARM: dts: r8a7793: Convert to new LVDS DT bindings
> >   ARM: dts: r8a7794: Convert to new DU DT bindings
> >   arm64: dts: renesas: r8a7795: Convert to new LVDS DT bindings
> >   arm64: dts: renesas: r8a7796: Convert to new LVDS DT bindings
> > 
> > Pantelis Antoniou (5):
> >   of: dynamic: Add __of_node_dupv()
> >   of: changesets: Introduce changeset helper methods
> >   of: changeset: Add of_changeset_node_move method
> >   of: unittest: changeset helpers
> >   i2c: demux: Use changeset helpers for clarity
> >  
> >  .../bindings/display/bridge/renesas,lvds.txt       |  56 +++
> >  .../devicetree/bindings/display/renesas,du.txt     |  31 +-
> >  MAINTAINERS                                        |   1 +
> >  arch/arm/boot/dts/r8a7790-lager.dts                |  22 +-
> >  arch/arm/boot/dts/r8a7790.dtsi                     |  64 ++-
> >  arch/arm/boot/dts/r8a7791-koelsch.dts              |  10 +-
> >  arch/arm/boot/dts/r8a7791-porter.dts               |  16 +-
> >  arch/arm/boot/dts/r8a7791.dtsi                     |  36 +-
> >  arch/arm/boot/dts/r8a7792.dtsi                     |   1 -
> >  arch/arm/boot/dts/r8a7793-gose.dts                 |  10 +-
> >  arch/arm/boot/dts/r8a7793.dtsi                     |  37 +-
> >  arch/arm/boot/dts/r8a7794.dtsi                     |   1 -
> >  .../boot/dts/renesas/r8a7795-es1-salvator-x.dts    |   3 +-
> >  arch/arm64/boot/dts/renesas/r8a7795-h3ulcb.dts     |   3 +-
> >  arch/arm64/boot/dts/renesas/r8a7795-salvator-x.dts |   3 +-
> >  .../arm64/boot/dts/renesas/r8a7795-salvator-xs.dts |   3 +-
> >  arch/arm64/boot/dts/renesas/r8a7795.dtsi           |  36 +-
> >  arch/arm64/boot/dts/renesas/r8a7796-m3ulcb.dts     |   3 +-
> >  arch/arm64/boot/dts/renesas/r8a7796-salvator-x.dts |   3 +-
> >  arch/arm64/boot/dts/renesas/r8a7796.dtsi           |  36 +-
> >  drivers/gpu/drm/rcar-du/Kconfig                    |   6 +-
> >  drivers/gpu/drm/rcar-du/Makefile                   |  10 +-
> >  drivers/gpu/drm/rcar-du/rcar_du_drv.c              |  21 +-
> >  drivers/gpu/drm/rcar-du/rcar_du_drv.h              |   5 -
> >  drivers/gpu/drm/rcar-du/rcar_du_encoder.c          | 175 +------
> >  drivers/gpu/drm/rcar-du/rcar_du_encoder.h          |  12 -
> >  drivers/gpu/drm/rcar-du/rcar_du_kms.c              |  14 +-
> >  drivers/gpu/drm/rcar-du/rcar_du_lvdscon.c          |  93 ----
> >  drivers/gpu/drm/rcar-du/rcar_du_lvdscon.h          |  24 -
> >  drivers/gpu/drm/rcar-du/rcar_du_lvdsenc.c          | 238 ----------
> >  drivers/gpu/drm/rcar-du/rcar_du_lvdsenc.h          |  64 ---
> >  drivers/gpu/drm/rcar-du/rcar_du_of.c               | 307 ++++++++++++
> >  drivers/gpu/drm/rcar-du/rcar_du_of.h               |  20 +
> >  .../gpu/drm/rcar-du/rcar_du_of_lvds_r8a7790.dts    |  81 ++++
> >  .../gpu/drm/rcar-du/rcar_du_of_lvds_r8a7791.dts    |  55 +++
> >  .../gpu/drm/rcar-du/rcar_du_of_lvds_r8a7793.dts    |  55 +++
> >  .../gpu/drm/rcar-du/rcar_du_of_lvds_r8a7795.dts    |  55 +++
> >  .../gpu/drm/rcar-du/rcar_du_of_lvds_r8a7796.dts    |  55 +++
> >  drivers/gpu/drm/rcar-du/rcar_lvds.c                | 524 ++++++++++++++++
> >  drivers/i2c/muxes/i2c-demux-pinctrl.c              |  12 +-
> >  drivers/of/dynamic.c                               | 317 ++++++++++++-
> >  drivers/of/unittest.c                              |  54 +++
> >  include/linux/of.h                                 | 337 +++++++++++++
> >  43 files changed, 2199 insertions(+), 710 deletions(-)
> >  create mode 100644
> >  Documentation/devicetree/bindings/display/bridge/renesas,lvds.txt delete
> >  mode 100644 drivers/gpu/drm/rcar-du/rcar_du_lvdscon.c
> >  delete mode 100644 drivers/gpu/drm/rcar-du/rcar_du_lvdscon.h
> >  delete mode 100644 drivers/gpu/drm/rcar-du/rcar_du_lvdsenc.c
> >  delete mode 100644 drivers/gpu/drm/rcar-du/rcar_du_lvdsenc.h
> >  create mode 100644 drivers/gpu/drm/rcar-du/rcar_du_of.c
> >  create mode 100644 drivers/gpu/drm/rcar-du/rcar_du_of.h
> >  create mode 100644 drivers/gpu/drm/rcar-du/rcar_du_of_lvds_r8a7790.dts
> >  create mode 100644 drivers/gpu/drm/rcar-du/rcar_du_of_lvds_r8a7791.dts
> >  create mode 100644 drivers/gpu/drm/rcar-du/rcar_du_of_lvds_r8a7793.dts
> >  create mode 100644 drivers/gpu/drm/rcar-du/rcar_du_of_lvds_r8a7795.dts
> >  create mode 100644 drivers/gpu/drm/rcar-du/rcar_du_of_lvds_r8a7796.dts
> >  create mode 100644 drivers/gpu/drm/rcar-du/rcar_lvds.c

-- 
Regards,

Laurent Pinchart

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