Re: [PATCH 00/60] drm/omap: Replace custom display drivers with drm_bridge and drm_panel

[Daniel Vetter <daniel@ffwll.ch>]

On Sun, Jul 07, 2019 at 09:07:52PM +0300, Laurent Pinchart wrote:
> Hello,
> 
> This patch series (nearly, see [1]) completes the rework of the omapdrm
> driver to move to drm_bridge and drm_panel.
> 
> What a journey. This work was started more than a year ago, and this
> last piece is perhaps the one that will generate the most bikeshedding
> as it touches the DRM core. I'm braced for the impact, but please be
> gentle :-)
> 
> Let's start with some context to understand the problem. omapdrm
> contains custom drivers for external encoders, panels and connectors
> (collectively referred to as display drivers). It combines them to
> create output pipelines abstracted by a drm_encoder and a drm_connector,
> with the ability to delegate the encoder and connector operations to the
> component in the pipeline that implements them. For instance, for an
> HDMI output pipeline, the hot plug detection and the EDID read can be
> implemented by two different components, when they are handled by two
> different devices at the hardware level.
> 
> DRM/KMS uses drm_bridge and drm_panel to abstract external encoders and
> panels. The model is however simpler than what omapdrm provides, as
> bridges were designed to be simple add-ons at the output of a
> drm_encoder. The ability to chain bridges exists, but a bridge driver
> hardcodes in its design its position in the pipeline : bridges that
> expect to terminate the pipeline create a drm_connector, while bridges
> that expect to be an intermediate component in the pipeline do not
> create a connector. In addition to not supporting bridges that can be
> either internal or a termination point in the pipeline depending on the
> hardware design, implementing the drm_connector inside a bridge driver
> makes it impossible to support hardware where bridge operations are
> handled by different hardware components, as explained above.
> 
> The omapdrm driver has received support for drm_bridge and drm_panel,
> but these issues prevented completely moving away from the omapdrm
> custom display drivers. This patch series thus first reworks the
> drm_bridge infrastructure to support the omapdrm use cases, and then
> transitions the omapdrm driver.
> 
> The series starts by 01/60 that adds a new flag to the drm_display_info
> structure to identify HDMI sinks. This is a feature needed by the OMAP4
> and OMAP5 HDMI encoders, and I believe it can be useful to other HDMI
> encoders as well. 02/60 is then a small drive-by cleanup.
> 
> The first sizeable change follows with the rename of the dumb-vga-dac
> driver to simple-bridge (03/60 and 04/60) and support for non-VGA
> bridges (05/60). This doesn't change the spirit of the driver that still
> focusses on transparent bridges, but prepares it to support an analog
> video amplifier. Patches 06/60 then add support for an enable GPIO, and
> 07/60 support for the OPA362 video amplifier itself.
> 
> The next two patches address the drm_bridge issues explained above.
> Patch 08/60 makes it possible to attach to a bridge without having the
> bridge create a connector. The connector is expected to be created by
> the display controller driver. Patch 09/60 adds connector-related
> operations to drm_bridge to make this possible.
> 
> The approach taken here is slightly intrusive as path 08/60 adds a
> parameter to tbe bridge .attach() operation, and thus touches all bridge
> drivers, even if the changes are very simple (as a consequence I haven't
> CC'ed all the individual bridge maintainers as the CC list was too
> large). Other options may be possible, what matters most to me is the
> feature, not so much its implementation. Please note that I envision the
> parameter to be removed down the road once all bridge drivers will be
> converted to the new model (but this will likely take time, and both
> models can co-exist for as long as necessary).
> 
> The next six patches make use of these new features: patches 10/60 and
> 11/60 add new bridge drivers for display connectors and for the TI
> TPD12S015 HDMI level shifter respectively, patch 12/60 supports the new
> API in the panel bridge driver, and patches 13/60 to 15/60 do the same
> in the ti-tfp410 driver.
> 
> The nine patches that follow add support for six new panels, with the
> related DT bindings (16/60 to 18/60) and the drm_panel drivers (19/60 to
> 24/60). The code originates from the corresponding omapdrm-specific
> panel drivers (which explains why only three DT patches are needed as
> most of the bindings are already present).
> 
> Patch 25/60 is possibly the most remarkable one in the series, with the
> drm_bridge operations extension, as it provides a helper for display
> controller drivers to construct a drm_connector entirerly backed by a
> chain of bridges. This offsets the complexity of the additional bridge
> operations by handling it all in a single place. An example usage for
> omapdrm can be found in patch 43/60. Don't let its diffstat mislead you,
> usage of the helper would remove lots of code if it wasn't for the fact
> that the legacy implementation still has to be kept for the DSI panel
> (see [1]). Down the road this helper and the new operation paradigm
> should remove code from both display controller and bridge drivers.
> 
> The rest of the series is omapdrm-focussed, slowly preparing the driver
> for the switch to drm_bridge drivers using the new helper (43/60), the
> removal of the omapdrm-specific display drivers (44/60 and 50/60), and
> lots of simplification and code removal in the other patches.

git branch pls, thanks.

> [1] The only notable exception is the omapdrm-specific DSI panel driver
> that implements a large number of custom operations. This should be
> addressed separately.

DSI tends to be fairly custom in all drivers, I think that's totally fine.
Maybe not forever, but we have a lot worse crimes in our codebase than
that :-)

-Daniel

> 
> Laurent Pinchart (60):
>   drm/edid: Add flag to drm_display_info to identify HDMI sinks
>   video: hdmi: Change return type of hdmi_avi_infoframe_init() to void
>   drm/bridge: dumb-vga-dac: Rename internal symbols to simple-bridge
>   drm/bridge: dumb-vga-dac: Rename driver to simple-bridge
>   drm/bridge: simple-bridge: Add support for non-VGA bridges
>   drm/bridge: simple-bridge: Add support for enable GPIO
>   drm/bridge: simple-bridge: Add support for the TI OP362
>   drm/bridge: Extend bridge API to disable connector creation
>   drm/bridge: Add connector-related bridge operations and data
>   drm/bridge: Add bridge driver for display connectors
>   drm/bridge: Add driver for the TI TPD12S015 HDMI level shifter
>   drm/bridge: panel: Implement bridge connector operations
>   drm/bridge: tfp410: Don't include drmP.h
>   drm/bridge: tfp410: Replace manual connector handling with bridge
>   drm/bridge: tfp410: Allow operation without drm_connector
>   dt-bindings: Add vendor prefix for LG Display
>   dt-bindings: Add legacy 'toppoly' vendor prefix
>   dt-bindings: display: panel: Add bindings for NEC NL8048HL11 panel
>   drm/panel: Add driver for the LG Philips LB035Q02 panel
>   drm/panel: Add driver for the NEC NL8048HL11 panel
>   drm/panel: Add driver for the Sharp LS037V7DW01 panel
>   drm/panel: Add driver for the Sony ACX565AKM panel
>   drm/panel: Add driver for the Toppology TD028TTEC1 panel
>   drm/panel: Add driver for the Toppology TD043MTEA1 panel
>   drm: Add helper to create a connector for a chain of bridges
>   drm/omap: Detach from panels at remove time
>   drm/omap: Simplify HDMI mode and infoframe configuration
>   drm/omap: Factor out display type to connector type conversion
>   drm/omap: Use the drm_panel_bridge API
>   drm/omap: dss: Fix output next device lookup in DT
>   drm/omap: Add infrastructure to support drm_bridge local to DSS
>     outputs
>   drm/omap: dss: Make omap_dss_device_ops optional
>   drm/omap: hdmi: Allocate EDID in the .read_edid() operation
>   drm/omap: hdmi4: Rework EDID read to isolate data read
>   drm/omap: hdmi5: Rework EDID read to isolate data read
>   drm/omap: hdmi4: Register a drm_bridge for EDID read
>   drm/omap: hdmi5: Register a drm_bridge for EDID read
>   drm/omap: hdmi4: Move mode set, enable and disable operations to
>     bridge
>   drm/omap: hdmi5: Move mode set, enable and disable operations to
>     bridge
>   drm/omap: hdmi4: Implement drm_bridge .lost_hotplug() operation
>   drm/omap: dss: Remove .set_hdmi_mode() and .set_infoframe() operations
>   drm/omap: venc: Register a drm_bridge
>   drm/omap: Create connector for bridges
>   drm/omap: Switch the HDMI and VENC outputs to drm_bridge
>   drm/omap: Remove HPD, detect and EDID omapdss operations
>   drm/omap: hdmi: Remove omap_dss_device operations
>   drm/omap: venc: Remove omap_dss_device operations
>   drm/omap: hdmi4: Simplify EDID read
>   drm/omap: hdmi5: Simplify EDID read
>   drm/omap: displays: Remove unused panel drivers
>   drm/omap: dpi: Sort includes alphabetically
>   drm/omap: dpi: Reorder functions in sections
>   drm/omap: dpi: Simplify clock setting API
>   drm/omap: dpi: Register a drm_bridge
>   drm/omap: sdi: Sort includes alphabetically
>   drm/omap: sdi: Register a drm_bridge
>   drm/omap: Simplify connector implementation
>   drm/omap: dss: Remove unused omap_dss_device operations
>   drm/omap: dss: Inline the omapdss_display_get() function
>   drm/omap: dss: Remove unused omapdss_of_find_connected_device()
>     function
> 
>  .../bindings/display/panel/nec,nl8048hl11.txt |  38 +
>  .../devicetree/bindings/vendor-prefixes.yaml  |   4 +
>  arch/arm/configs/davinci_all_defconfig        |   2 +-
>  arch/arm/configs/integrator_defconfig         |   2 +-
>  arch/arm/configs/multi_v7_defconfig           |   2 +-
>  arch/arm/configs/shmobile_defconfig           |   2 +-
>  arch/arm/configs/sunxi_defconfig              |   2 +-
>  arch/arm/configs/versatile_defconfig          |   2 +-
>  drivers/gpu/drm/Makefile                      |   3 +-
>  drivers/gpu/drm/arc/arcpgu_hdmi.c             |   2 +-
>  .../gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c  |   2 +-
>  drivers/gpu/drm/bridge/Kconfig                |  29 +-
>  drivers/gpu/drm/bridge/Makefile               |   4 +-
>  drivers/gpu/drm/bridge/adv7511/adv7511_drv.c  |   6 +-
>  drivers/gpu/drm/bridge/analogix-anx78xx.c     |   6 +-
>  .../drm/bridge/analogix/analogix_dp_core.c    |   8 +-
>  drivers/gpu/drm/bridge/cdns-dsi.c             |   6 +-
>  drivers/gpu/drm/bridge/display-connector.c    | 327 ++++++++
>  drivers/gpu/drm/bridge/dumb-vga-dac.c         | 296 -------
>  drivers/gpu/drm/bridge/lvds-encoder.c         |   4 +-
>  .../bridge/megachips-stdpxxxx-ge-b850v3-fw.c  |   6 +-
>  drivers/gpu/drm/bridge/nxp-ptn3460.c          |   6 +-
>  drivers/gpu/drm/bridge/panel.c                |  21 +-
>  drivers/gpu/drm/bridge/parade-ps8622.c        |   5 +-
>  drivers/gpu/drm/bridge/sii902x.c              |   6 +-
>  drivers/gpu/drm/bridge/sil-sii8620.c          |   2 +-
>  drivers/gpu/drm/bridge/simple-bridge.c        | 337 ++++++++
>  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c     |   8 +-
>  drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c |   8 +-
>  drivers/gpu/drm/bridge/tc358764.c             |   5 +-
>  drivers/gpu/drm/bridge/tc358767.c             |   5 +-
>  drivers/gpu/drm/bridge/thc63lvd1024.c         |   5 +-
>  drivers/gpu/drm/bridge/ti-sn65dsi86.c         |   5 +-
>  drivers/gpu/drm/bridge/ti-tfp410.c            | 202 ++---
>  drivers/gpu/drm/bridge/ti-tpd12s015.c         | 204 +++++
>  drivers/gpu/drm/drm_bridge.c                  |  97 ++-
>  drivers/gpu/drm/drm_bridge_connector.c        | 385 +++++++++
>  drivers/gpu/drm/drm_edid.c                    |   8 +-
>  drivers/gpu/drm/drm_simple_kms_helper.c       |   2 +-
>  drivers/gpu/drm/exynos/exynos_dp.c            |   3 +-
>  drivers/gpu/drm/exynos/exynos_drm_dsi.c       |   4 +-
>  drivers/gpu/drm/exynos/exynos_hdmi.c          |   2 +-
>  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c     |   2 +-
>  drivers/gpu/drm/hisilicon/kirin/dw_drm_dsi.c  |   2 +-
>  drivers/gpu/drm/i2c/tda998x_drv.c             |   8 +-
>  drivers/gpu/drm/imx/imx-ldb.c                 |   2 +-
>  drivers/gpu/drm/imx/parallel-display.c        |   2 +-
>  drivers/gpu/drm/mcde/mcde_dsi.c               |   6 +-
>  drivers/gpu/drm/mediatek/mtk_dpi.c            |   2 +-
>  drivers/gpu/drm/mediatek/mtk_dsi.c            |   2 +-
>  drivers/gpu/drm/mediatek/mtk_hdmi.c           |   8 +-
>  drivers/gpu/drm/msm/dsi/dsi_manager.c         |   4 +-
>  drivers/gpu/drm/msm/edp/edp_bridge.c          |   2 +-
>  drivers/gpu/drm/msm/hdmi/hdmi_bridge.c        |   2 +-
>  drivers/gpu/drm/omapdrm/displays/Kconfig      |  60 --
>  drivers/gpu/drm/omapdrm/displays/Makefile     |  10 -
>  .../omapdrm/displays/connector-analog-tv.c    | 100 ---
>  .../gpu/drm/omapdrm/displays/connector-hdmi.c | 186 -----
>  .../gpu/drm/omapdrm/displays/encoder-opa362.c | 140 ----
>  .../drm/omapdrm/displays/encoder-tpd12s015.c  | 220 -----
>  .../gpu/drm/omapdrm/displays/panel-dsi-cm.c   |   2 +-
>  .../displays/panel-lgphilips-lb035q02.c       | 254 ------
>  .../omapdrm/displays/panel-nec-nl8048hl11.c   | 271 -------
>  .../displays/panel-sharp-ls037v7dw01.c        | 265 ------
>  .../omapdrm/displays/panel-sony-acx565akm.c   | 766 ------------------
>  .../omapdrm/displays/panel-tpo-td028ttec1.c   | 401 ---------
>  .../omapdrm/displays/panel-tpo-td043mtea1.c   | 513 ------------
>  drivers/gpu/drm/omapdrm/dss/Makefile          |   2 +-
>  drivers/gpu/drm/omapdrm/dss/base.c            |  72 +-
>  drivers/gpu/drm/omapdrm/dss/display.c         |   9 -
>  drivers/gpu/drm/omapdrm/dss/dpi.c             | 336 ++++----
>  drivers/gpu/drm/omapdrm/dss/dsi.c             |   4 +-
>  drivers/gpu/drm/omapdrm/dss/dss-of.c          |  28 -
>  drivers/gpu/drm/omapdrm/dss/dss.c             |   3 +-
>  drivers/gpu/drm/omapdrm/dss/hdmi.h            |   4 +-
>  drivers/gpu/drm/omapdrm/dss/hdmi4.c           | 321 ++++----
>  drivers/gpu/drm/omapdrm/dss/hdmi4_core.c      |  59 +-
>  drivers/gpu/drm/omapdrm/dss/hdmi4_core.h      |   4 +-
>  drivers/gpu/drm/omapdrm/dss/hdmi5.c           | 303 +++----
>  drivers/gpu/drm/omapdrm/dss/hdmi5_core.c      |  48 +-
>  drivers/gpu/drm/omapdrm/dss/hdmi5_core.h      |   5 +-
>  .../gpu/drm/omapdrm/dss/omapdss-boot-init.c   |  12 -
>  drivers/gpu/drm/omapdrm/dss/omapdss.h         |  47 +-
>  drivers/gpu/drm/omapdrm/dss/output.c          |  55 +-
>  drivers/gpu/drm/omapdrm/dss/sdi.c             | 187 +++--
>  drivers/gpu/drm/omapdrm/dss/venc.c            | 269 +++---
>  drivers/gpu/drm/omapdrm/omap_connector.c      | 246 +-----
>  drivers/gpu/drm/omapdrm/omap_connector.h      |   3 -
>  drivers/gpu/drm/omapdrm/omap_drv.c            |  98 ++-
>  drivers/gpu/drm/omapdrm/omap_encoder.c        |  83 +-
>  drivers/gpu/drm/panel/Kconfig                 |  44 +
>  drivers/gpu/drm/panel/Makefile                |   6 +
>  drivers/gpu/drm/panel/panel-lg-lb035q02.c     | 235 ++++++
>  drivers/gpu/drm/panel/panel-nec-nl8048hl11.c  | 249 ++++++
>  .../gpu/drm/panel/panel-sharp-ls037v7dw01.c   | 231 ++++++
>  drivers/gpu/drm/panel/panel-sony-acx565akm.c  | 691 ++++++++++++++++
>  drivers/gpu/drm/panel/panel-tpo-td028ttec1.c  | 382 +++++++++
>  drivers/gpu/drm/panel/panel-tpo-td043mtea1.c  | 510 ++++++++++++
>  drivers/gpu/drm/rcar-du/rcar_du_encoder.c     |   2 +-
>  drivers/gpu/drm/rcar-du/rcar_lvds.c           |   7 +-
>  drivers/gpu/drm/rockchip/rockchip_lvds.c      |   2 +-
>  drivers/gpu/drm/rockchip/rockchip_rgb.c       |   2 +-
>  drivers/gpu/drm/sti/sti_dvo.c                 |   2 +-
>  drivers/gpu/drm/sti/sti_hda.c                 |   2 +-
>  drivers/gpu/drm/sti/sti_hdmi.c                |   2 +-
>  drivers/gpu/drm/stm/ltdc.c                    |   2 +-
>  drivers/gpu/drm/sun4i/sun4i_lvds.c            |   2 +-
>  drivers/gpu/drm/sun4i/sun4i_rgb.c             |   2 +-
>  drivers/gpu/drm/tilcdc/tilcdc_external.c      |   2 +-
>  drivers/gpu/drm/vc4/vc4_dpi.c                 |   2 +-
>  drivers/gpu/drm/vc4/vc4_dsi.c                 |   2 +-
>  drivers/video/hdmi.c                          |   9 +-
>  include/drm/drm_bridge.h                      | 174 +++-
>  include/drm/drm_bridge_connector.h            |  18 +
>  include/drm/drm_connector.h                   |   5 +
>  include/linux/hdmi.h                          |   2 +-
>  116 files changed, 5188 insertions(+), 4900 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/display/panel/nec,nl8048hl11.txt
>  create mode 100644 drivers/gpu/drm/bridge/display-connector.c
>  delete mode 100644 drivers/gpu/drm/bridge/dumb-vga-dac.c
>  create mode 100644 drivers/gpu/drm/bridge/simple-bridge.c
>  create mode 100644 drivers/gpu/drm/bridge/ti-tpd12s015.c
>  create mode 100644 drivers/gpu/drm/drm_bridge_connector.c
>  delete mode 100644 drivers/gpu/drm/omapdrm/displays/connector-analog-tv.c
>  delete mode 100644 drivers/gpu/drm/omapdrm/displays/connector-hdmi.c
>  delete mode 100644 drivers/gpu/drm/omapdrm/displays/encoder-opa362.c
>  delete mode 100644 drivers/gpu/drm/omapdrm/displays/encoder-tpd12s015.c
>  delete mode 100644 drivers/gpu/drm/omapdrm/displays/panel-lgphilips-lb035q02.c
>  delete mode 100644 drivers/gpu/drm/omapdrm/displays/panel-nec-nl8048hl11.c
>  delete mode 100644 drivers/gpu/drm/omapdrm/displays/panel-sharp-ls037v7dw01.c
>  delete mode 100644 drivers/gpu/drm/omapdrm/displays/panel-sony-acx565akm.c
>  delete mode 100644 drivers/gpu/drm/omapdrm/displays/panel-tpo-td028ttec1.c
>  delete mode 100644 drivers/gpu/drm/omapdrm/displays/panel-tpo-td043mtea1.c
>  delete mode 100644 drivers/gpu/drm/omapdrm/dss/dss-of.c
>  create mode 100644 drivers/gpu/drm/panel/panel-lg-lb035q02.c
>  create mode 100644 drivers/gpu/drm/panel/panel-nec-nl8048hl11.c
>  create mode 100644 drivers/gpu/drm/panel/panel-sharp-ls037v7dw01.c
>  create mode 100644 drivers/gpu/drm/panel/panel-sony-acx565akm.c
>  create mode 100644 drivers/gpu/drm/panel/panel-tpo-td028ttec1.c
>  create mode 100644 drivers/gpu/drm/panel/panel-tpo-td043mtea1.c
>  create mode 100644 include/drm/drm_bridge_connector.h
> 
> -- 
> Regards,
> 
> Laurent Pinchart
> 

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