Re: [PATCH v4 00/11] drm: Add Allwinner A10 display engine support

[Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>]

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On Mon, Apr 25, 2016 at 03:22:41PM +0200, Maxime Ripard wrote:
> Hi everyone,
> 
> The Allwinner SoCs (except for the very latest ones) all share the
> same set of controllers, loosely coupled together to form the display
> pipeline.
> 
> Depending on the SoC, the number of instances of the controller will
> change (2 instances of each in the A10, only one in the A13, for
> example), and the output availables will change too (HDMI, composite,
> VGA on the A20, none of them on the A13).
> 
> On most featured SoCs, it looks like that:
> 
> +--------------------------------------------+
> |                    RAM                     |
> +--------------------------------------------+
>       |            |      |            |
>       v            |      |            v
> +----------------+ |      | +----------------+
> |    Frontend    | |      | |    Frontend    |
> +----------------+ |      | +----------------+
>         |          |      |         |
>         v          |      |         v
> +----------------+ |      | +----------------+
> |    Backend     |<+      +>|    Backend     |
> +----------------+          +----------------+
>         |                           |
>         v                           v
> +----------------+          +----------------+---> LVDS
> |      TCON      |          |      TCON      |---> RGB
> +----------------+          +----------------+
>       |       +---+       +---+          |
>       |           |       |              |
>       v           v       v              v
> +------------+  +------------+  +------------+---> VGA
> | TV Encoder |  |    HDMI    |  | TV Encoder |---> Composite
> +------------+  +------------+  +------------+
> 
> The current code only assumes that there is a single instance of all
> the controllers. It also supports only the RGB and Composite
> interfaces.
> 
> Let me know what you think,
> Maxime
> 
> Changes from v3:
>   - Fixed a circular dependency issue found when building as a module
>   - Changed a bit the mode_valid checks
>   - Fixed an issue with the timings generated by the display engine
> 
>   - Changed the DT bindings according to Rob feedback (removed the
>     allwinner,panel property, documented the endpoints indices, always
>     use the frontend as the pipeline entrypoint)
> 
>   - Changed the display clocks according to Stephen comments (marked
>     structures as const, changed a variable name)
> 
> Changes from v2:
>   - Rebased on top of next-20160318
> 
>   - Dropped the generic clock regmap conversion and implemented a
>     custom clock for our pixel clock, backed by a regmap
>   - Added the reset bits for the tcon channel 0 and display clocks
>   - Used the new generic gates compatible for the DRAM gates
>   - Few clock fixes (missing iounmap, return error checks, etc)
>   - Found out that the TCON channel 1 clock was not operating properly
>     because of some weird rounding down and up between the various
>     generic clocks involved. Rewrote it using custom operations
> 
>   - Removed some TODO that were still there
>   - Converted our panel DT description to the OF graph instead of a
>     custom property
>   - Tested the driver on a setup where U-Boot was not initialising the
>     display, or initialising it on a different output, and fixed a
>     number of associated bugs (mostly related to missing
>     initialisation bits, missing reset handles, and so on)
>   - Fixed the layer code that was assuming that the X and Y
>     coordinates were in pixels, leading to a miscalculation of the
>     buffer address when those coordinates where set.
>   - Added the missing EXPORT_SYMBOL calls
> 
>   - Fixed our VBLANK interrupt code that was completely broken (and
>     not usable, which is why it was unnoticed)
> 
> Changes from v1:
>   - Rebased on top of 4.4
> 
>   - Merged the clock drivers for the display and TCON channel 0 clocks
>   - Replaced the container_of calls in the display reset clocks to an
>     inline function
>   - Checked the return code of of_clk_parent_fill in the clocks
>     drivers
>   - Checked the return code of of_clk_add_provider in the tcon-ch1 and
>     PLL3 clocks
>   - Added missing clocks headers
>   - Created a composite clock unregister function
> 
>   - Moved the binding documentation to
>     Documentation/devicetree/bindings/display
>   - Added the clocks binding documentation
>   - Added the Olimex vendor to the list of DT vendors
>   - Moved to the OF graph representation and the component framework
> 
>   - Moved the reset cells count check into the reset framework to
>     avoid duplicating the code in every xlate implementation.
>   - Made the reset_ops const
> 
>   - Reworked the DRM cmdline mode parsing code to allow named mode
>   - Fixed the TV mode lookup when the mode name is not present (for
>     example because it was given by the userspace)
> 
>   - Made the driver outputs optional (to avoid crashing when a board
>     doesn't have either a panel or a composite output enabled)
>   - Added multiple plane support with transparency
>   - Moved the backend registers writes commit in the CRTC atomic_flush
>     callback
>   - Removed the load / unload functions
>   - Removed the enabled booleans in my private structure and removed
>     the implicit call to disable_unused_functions in the DRM core to
>     push it in the drivers.
>   - Fixed a few bitmasks on some bitfields definition
>   - Fixed the RGB connector mode validation that was not testing the
>     right values				  

Applied the DT patches.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com