Subject: Re: [PATCH v11 0/2] drm: bridge: Add NWL MIPI DSI host controller support

From: Sam Ravnborg <[email-masked]>
Date: Thu, 9 Apr 2020 16:01:30 +0200

Hi Guido.

On Thu, Apr 09, 2020 at 12:42:00PM +0200, Guido Günther wrote:
> This adds initial support for the NWL MIPI DSI Host controller found on i.MX8
> SoCs.
> 
> It adds support for the i.MX8MQ but the same IP core can also be found on e.g.
> i.MX8QXP. I added the necessary hooks to support other imx8 variants but since
> I only have imx8mq boards to test I omitted the platform data for other SoCs.
> 
> The code is based on NXPs BSP so I added Robert Chiras as Co-authored-by.
> 
> The most notable changes over the BSP driver are
>  - Calculate HS mode timing from phy_configure_opts_mipi_dphy
>  - Perform all clock setup via DT
>  - Merge nwl-imx and nwl drivers
>  - Add B0 silion revision quirk
>  - become a bridge driver to hook into mxsfb / dcss
>    imx-display-subsystem so it makes sense to make it drive a bridge for dsi as
>    well).
>  - Use panel_bridge to attach the panel
>  - Use multiplex framework instead of accessing syscon directly
> 
> This has been tested on a Librem 5 devkit using mxsfb with Robert's patches[1]
> and the mainline rocktech-jh057n00900 DSI panel driver on next-20200317 and on
> the Librem5 with the a Mantix MLAF057WE51-X DSI panel driver (not yet mainline)
> The DCSS (submitted for mainline inclusion now too) can also act as input
> source.

Thanks for your persistence with this driver.
I got ack from Laurent on IRC to apply it (not for the driver as he had
no time to review it).
So applied to drm-misc-next now.

I look forward for the update to support DRM_BRIDGE_ATTACH_NO_CONNECTOR
in this driver and the corresponding display driver.

	Sam
> 
> Changes from v10:
> - Per review comments by Sam Ravnborg
>   https://lore.kernel.org/linux-arm-kernel/[email-masked]/
>   - Drop unused headers
>   - Fix 'check-patch --strict' findings
>   - Print error when DRM_BRIDGE_ATTACH_NO_CONNECTOR is passed
> - Per review comment by Laurent Pinchart
>   https://lore.kernel.org/linux-arm-kernel/[email-masked]/
>   - There's only one endpoint allowed at a time, add a restriction for that.
> - Add Reviewed-by from Fabio Estevam
>   https://lore.kernel.org/linux-arm-kernel/CAOMZO5Dhy7ahcR-S=QG=[email-masked]/
>   https://lore.kernel.org/linux-arm-kernel/[email-masked]/
> - Move to next-20200408
> 
> Changes from v9:
> - Per review comments by Sam Ravnborg
>   https://lore.kernel.org/dri-devel/[email-masked]/
>   - Drop header-test-y since kernel lost support
>   - Handle drm_bridge_attach's new flags argument
>   - Add Acked-by: to binding patch, thanks!
> - Move to next-20200319
> 
> Changes from v8:
> - Per review comments by Robert Chiras
>   https://lore.kernel.org/dri-devel/[email-masked]/
>   - don't mix DSI host and bridge initialization
>   - only select output source once
>   - defer probe when panel is not ready to fix usage as a module
>   - use correct reset sequence as described by Robert
>     (and provided by NWL)
>   - use mode->clock instead of mode->crtc_clock
> - Add tested by from Martin Kepplinger, thanks!
> - Drop platform specific data (as suggested previously by Laurent Pinchart and
>   Andrzej Hajda) since imx8q* needs another set of abstractions with the new
>   reset sequence and that's easier to do when adding imx8q* support rather then
>   adding wrong abstraction now.
> - Update bindings to use proper clock and irq names to make the example match
>   reality more closely.
> - Use `fallthrough;` instead of /* Fall through */ in switch statements
> - Move to next-20200226
> 
> Changes from v7:
> - Drop reset quirk. It's not needed with mxsfb and sometimes triggers a shifted display.
> 
> Changes from v6:
> - Per review comments by Andrzej Hajda
>   https://lore.kernel.org/linux-arm-kernel/[email-masked]/
>   - Drop spare empty line
>   - handle nwl_dsi_write errors
>   - better handle read errors
>   - unwind in case of error in nwl_dsi_enable
>   - use bridge_to_dsi() instead of accessing driver_private
>   - don't log on -EPROBEDEFER when fething the reset controller
>   - use endpoint number to determine input
> - Spotted by kbuild test robot <[email-masked]>
>   https://lore.kernel.org/linux-arm-kernel/[email-masked]/
>   Use signed return type for nwl_dsi_get_dpi_pixel_format
> - Drop connector type from drm_panel_bridge_add
> - Don't forget to set an error value on dsi reads
> 
> Changes from v5:
> - Per review comments by Andrzej Hajda
>   https://lists.freedesktop.org/archives/dri-devel/2019-September/235281.html
>   - Fix include file ordering
>   - Add a comment to nwl_dsi_platform_data that will allow to add support
>     at least for the i.MX8QM
>   - Merge driver into a single file plus the register defs in a separate header
> - Make more functions and structs static
> 
> Changes from v4:
> - Collect Reviewed-by: from Rob Herring, thanks!
>   https://lists.freedesktop.org/archives/dri-devel/2019-September/233979.html
> - Spotted by kbuild test robot <[email-masked]>
>   https://lists.freedesktop.org/archives/dri-devel/2019-September/233860.html
>   https://lists.freedesktop.org/archives/dri-devel/2019-September/233863.html
>   - fix format string for size_t
>   - Use DIV64_U64_ROUND_UP to fix build on 32 bit architectures
>     We can't use simple shift sind d and n are similar in size and
>     we need full precision
> - Fix debug cfg_t_post debug print out
> - Avoid PSEC_PER_SEC
> - Move timeout / overflow handling out of nwl_dsi_finish_transmission,
>   it would never end up being reported since the call to the function
>   was guarded by flags.
> - Drop 'support for' from KConfig title to make it match the other
>   drivers in that submenu
> 
> Changes from v3:
> - Per review comments by Robert Chiras
>   https://lists.freedesktop.org/archives/dri-devel/2019-August/232580.html
>   - Add Robert's {Signed-off,Tested}-by:
>   - Respect number of lanes when calculting bandwidth limits
>   - Drop duplicate NWL_DSI_ENABLE_MULT_PKTS setup
> - Per testing by Rober Chiras
>   https://lists.freedesktop.org/archives/dri-devel/2019-August/233688.html
>   - Drop duplicate (and too early) drm_bridge_add() in nwl_dsi_probe() that
>     made mxsfb fail to connect to the bridge since the panel_bridge was not up
>     yet. drm_bridge_add() happens in nwl_dsi_host_attach() where after the
>     panel_bridge was set up.
> - Per review comments by Rob Herring on bindings
>   https://lists.freedesktop.org/archives/dri-devel/2019-August/233196.html
>   - drop description from power-domains and resets
>   - allow BSD 2 clause license as well
>   - make ports more specific
>   - add #address-cells, #size-cells as required
>   - use additionalProperties
>   - panel is of type object
> 
> Changes from v2:
> - Per review comments by Rob Herring
>   https://lists.freedesktop.org/archives/dri-devel/2019-August/230448.html
>   - bindings:
>     - Simplify by restricting to fsl,imx8mq-nwl-dsi
>     - document reset lines
>     - add port@{0,1}
>     - use a real compatible string for the panel
>     - resets are required
> - Per review comments by Arnd Bergmann
>   https://lists.freedesktop.org/archives/dri-devel/2019-August/230868.html
>   - Don't access iomuxc_gpr regs directly. This allows us to drop the
>     first patch in the series with the iomuxc_gpr field defines.
> - Per review comments by Laurent Pinchart
>   Fix wording in bindings
> - Add mux-controls to bindings
> - Don't print error message on dphy probe deferral
> 
> Changes from v1:
> - Per review comments by Sam Ravnborg
>   https://lists.freedesktop.org/archives/dri-devel/2019-July/228130.html
>   - Change binding docs to YAML
>   - build: Don't always visit imx-nwl/
>   - build: Add header-test-y
>   - Sort headers according to DRM convention
>   - Use drm_display_mode instead of videmode
> - Per review comments by Fabio Estevam
>   https://lists.freedesktop.org/archives/dri-devel/2019-July/228299.html
>   - Don't restrict build to ARCH_MXC
>   - Drop unused includes
>   - Drop unreachable code in imx_nwl_dsi_bridge_mode_fixup()
>   - Drop remaining calls of dev_err() and use DRM_DEV_ERR()
>     consistently.
>   - Use devm_platform_ioremap_resource()
>   - Drop devm_free_irq() in probe() error path
>   - Use single line comments where sufficient
>   - Use <linux/time64.h> instead of defining USEC_PER_SEC
>   - Make input source select imx8 specific
>   - Drop <asm/unaligned.h> inclusion (after removal of get_unaligned_le32)
>   - Drop all EXPORT_SYMBOL_GPL() for functions used in the same module
>     but different source files.
>   - Drop nwl_dsi_enable_{rx,tx}_clock() by invoking clk_prepare_enable()
>     directly
>   - Remove pointless comment
> - Laurent Pinchart
>   https://lists.freedesktop.org/archives/dri-devel/2019-July/228313.html
>   https://lists.freedesktop.org/archives/dri-devel/2019-July/228308.html
>   - Drop (on iMX8MQ) unused csr regmap
>   - Use NWL_MAX_PLATFORM_CLOCKS everywhere
>   - Drop get_unaligned_le32() usage
>   - remove duplicate 'for the' in binding docs
>   - Don't include unused <linux/clk-provider.h>
>   - Don't include unused <linux/component.h>
>   - Drop dpms_mode for tracking state, trust the drm layer on that
>   - Use pm_runtime_put() instead of pm_runtime_put_sync()
>   - Don't overwrite encoder type
>   - Make imx_nwl_platform_data const
>   - Use the reset controller API instead of open coding that platform specific
>     part
>   - Use <linux/bitfield.h> intead of making up our own defines
>   - name mipi_dsi_transfer less generic: nwl_dsi_transfer
>   - ensure clean in .remove by calling mipi_dsi_host_unregister.
>   - prefix constants by NWL_DSI_
>   - properly format transfer_direction enum
>   - simplify platform clock handling
>   - Don't modify state in mode_fixup() and use mode_set() instead
>   - Drop bridge detach(), already handle by nwl_dsi_host_detach()
>   - Drop USE_*_QUIRK() macros
> - Drop (for now) unused clock defnitions. 'pixel' and 'bypass' clock will be
>   used for i.MX8 SoCs but since they're unused atm drop the definitions - but
>   keep the logic to enable/disable several clocks in place since we know we'll
>   need it in the future.
> 
> Changes from v0:
> - Add quirk for IMQ8MQ silicon B0 revision to not mess with the
>   system reset controller on power down since enable() won't work
>   otherwise.
> - Drop devm_free_irq() handled by the device driver core
> - Disable tx esc clock after the phy power down to unbreak
>   disable/enable (unblank/blank)
> - Add ports to dt binding docs
> - Select GENERIC_PHY_MIPI_DPHY instead of GENERIC_PHY for
>   phy_mipi_dphy_get_default_config
> - Select DRM_MIPI_DSI
> - Include drm_print.h to fix build on next-20190408
> - Drop some debugging messages
> - Newline terminate all DRM_ printouts
> - Turn component driver into a drm bridge
> 
> [0]: https://lists.freedesktop.org/archives/dri-devel/2019-May/219484.html
> [1]: https://patchwork.freedesktop.org/series/62822/
> 
> Guido Günther (2):
>   dt-bindings: display/bridge: Add binding for NWL mipi dsi host
>     controller
>   drm/bridge: Add NWL MIPI DSI host controller support
> 
>  .../bindings/display/bridge/nwl-dsi.yaml      |  226 +++
>  drivers/gpu/drm/bridge/Kconfig                |   16 +
>  drivers/gpu/drm/bridge/Makefile               |    1 +
>  drivers/gpu/drm/bridge/nwl-dsi.c              | 1213 +++++++++++++++++
>  drivers/gpu/drm/bridge/nwl-dsi.h              |  144 ++
>  5 files changed, 1600 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/display/bridge/nwl-dsi.yaml
>  create mode 100644 drivers/gpu/drm/bridge/nwl-dsi.c
>  create mode 100644 drivers/gpu/drm/bridge/nwl-dsi.h
> 
> -- 
> 2.23.0
> 
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