Re: [PATCH 2/2] drm/verisilicon: add support for Nuvoton MA35D1 DCUltra Lite display controller

[Joey Lu <a0987203069@gmail.com>]

On 5/12/2026 4:24 PM, Thomas Zimmermann wrote:
> Hi,
>
> instead of this if-else branchery, I strongly recommend to add a new 
> file with a new mode-setting pipeline for the new chipset. You can 
> share existing helpers where possible, and implement variants where 
> chips differ.  It's a bit more code, but will be a lot easier to 
> maintain in the future.
>
> See ast and mgag200 for example. Both drivers support various 
> revisions of their chipset, where each rev has its oddities.
>
> Best regards
> Thomas

Thank you for the detailed suggestion.

I see your point and will refactor by adding a new file with a 
mode-setting pipeline for the chipset, reusing helpers where possible 
and handling variants as needed.

>
> Am 11.05.26 um 09:51 schrieb Joey Lu:
>> The Nuvoton MA35D1 SoC integrates a Verisilicon DCUltra Lite display
>> controller, which is a previous generation of the DC8000 series. While
>> the general register layout is similar to the DC8000, there are several
>> key differences that require per-variant handling in the driver.
>>
>> Add a vs_dc_info platform data structure (in vs_hwdb.h) to describe
>> per-IP-variant capabilities, and use it throughout the driver to select
>> the correct code paths at runtime.
>>
>> Key differences between DC8000 and DCUltra Lite handled:
>>
>> 1. No chip identity registers (0x0020-0x0030): DCUltra Lite uses static
>>     platform data instead of reading model/revision/customer_id from HW.
>>
>> 2. No CONFIG_EX commit mechanism: DC8000 uses registers at 0x1CC0
>>     (FB_CONFIG_EX), 0x24D8 (FB_TOP_LEFT), 0x24E0 (FB_BOTTOM_RIGHT),
>>     0x2510 (FB_BLEND_CONFIG), 0x2518 (PANEL_CONFIG_EX). DCUltra Lite
>>     omits all of these and instead uses enable/reset bits in FB_CONFIG
>>     (bit 0 = enable, bit 4 = reset) for direct framebuffer updates.
>>
>> 3. No PANEL_START register (0x1CCC): DCUltra Lite panel output starts
>>     when PANEL_CONFIG.RUNNING is set; no separate multi-display sync
>>     start register is needed.
>>
>> 4. Different IRQ registers: DCUltra Lite uses 0x147C (IRQ_STA) /
>>     0x1480 (IRQ_EN); DC8000 uses 0x0010 (IRQ_ACK) / 0x0014 (IRQ_EN).
>>
>> 5. Different clock/reset topology: DCUltra Lite requires only "core"
>>     (bus gate) and "pix0" (pixel divider) clocks with no reset lines
>>     managed by the driver. DC8000 needs core/axi/ahb clocks and three
>>     resets.
>>
>> 6. Single output only: DCUltra Lite has one display output; per-output
>>     index logic is still in place but display_count is fixed at 1.
>>
>> 7. Reduced register space: max_register is 0x2000 vs DC8000's 0x2544.
>>
>> Add the "nuvoton,ma35d1-dcu" compatible string to the OF match table,
>> extend Kconfig to allow building on ARCH_MA35 platforms, and expose
>> vs_formats_no_yuv444 as the default format table for DCUltra Lite
>> (YUV444 blending is a DC8000-only feature).
>>
>> All changes have been tested on Nuvoton MA35D1 hardware and are
>> functioning correctly.
>>
>> Signed-off-by: Joey Lu <a0987203069@gmail.com>
>> ---
>>   drivers/gpu/drm/verisilicon/Kconfig           |   2 +-
>>   drivers/gpu/drm/verisilicon/vs_bridge.c       |  28 ++--
>>   drivers/gpu/drm/verisilicon/vs_crtc.c         |  13 +-
>>   drivers/gpu/drm/verisilicon/vs_dc.c           | 129 ++++++++++++------
>>   drivers/gpu/drm/verisilicon/vs_dc.h           |   1 +
>>   drivers/gpu/drm/verisilicon/vs_drm.c          |  16 ++-
>>   drivers/gpu/drm/verisilicon/vs_hwdb.c         |   2 +-
>>   drivers/gpu/drm/verisilicon/vs_hwdb.h         |  25 ++++
>>   .../gpu/drm/verisilicon/vs_primary_plane.c    |  43 +++---
>>   .../drm/verisilicon/vs_primary_plane_regs.h   |   2 +
>>   10 files changed, 187 insertions(+), 74 deletions(-)
>>
>>
>