Information: The Microchip PIC32MZDA's GPU may also be GC200

[ReimuNotMoe]

Hello. These days I'm trying to understand how the GPU of Microchip PIC32MZDA works by reverse engineering its "nano2d" closed source driver. I googled the strings found in the static library and then found this repo (wow). After some peeking, I suspect it is actually a GC200. Is there a way to confirm this?

The strings I found in this driver:

Symbols in this driver:

➜  ~ nm libnano2d.a|grep -E '(n2d|gco)'
         U gcoHARDWARE_Clear2D
         U gcoHARDWARE_ConvertFormat
         U gcoHARDWARE_FilterBlit
         U gcoHARDWARE_GetStretchFactor
         U gcoHARDWARE_SetDither2D
         U gcoHARDWARE_StartDE
         U gcoHARDWARE_StartDELine
00000f8c T n2d_allocate
000016c0 T n2d_blit
00000000 t _n2d_check_context
000012f8 T n2d_commit
0000259c T n2d_dither
000011fc T n2d_draw_state
000013a4 T n2d_fill
000025fc T n2d_init_hardware
         U n2d_kernel_hardware_commit
         U n2d_kernel_hardware_query_chip_identity
         U n2d_kernel_os_allocate_contiguous
         U n2d_kernel_os_get_hardware_address
00001f60 T n2d_line
0000244c T n2d_load_palette
00000e04 T n2d_open
00002344 T n2d_set_global_alpha
         U n2d_user_hardware_initialize
000001f8 C s_gco2D
000022f0 T gcoHARDWARE_Clear2D
000051cc T gcoHARDWARE_ColorConvertFromARGB8
000054d0 T gcoHARDWARE_ColorConvertToARGB8
00004b64 T gcoHARDWARE_ConvertFormat
00003e44 T gcoHARDWARE_DisableAlphaBlend
00003ea8 T gcoHARDWARE_EnableAlphaBlend
000072d8 T gcoHARDWARE_End2DFrame
00006cc4 T gcoHARDWARE_FilterBlit
00003980 T gcoHARDWARE_Get2DResourceUsage
00004288 T gcoHARDWARE_GetStretchFactor
00003674 T gcoHARDWARE_Load2DState
000036d0 T gcoHARDWARE_Load2DState32
00005868 T gcoHARDWARE_LoadColorPattern
000079b4 T gcoHARDWARE_LoadPalette
000050a4 T gcoHARDWARE_LoadSolidColorPattern
0000740c T gcoHARDWARE_Reset2DCmdBuffer
00003720 T gcoHARDWARE_Set2DClearColor
0000239c t gcoHARDWARE_Set2DState
00003768 T gcoHARDWARE_SetBitBlitMirror
0000357c T gcoHARDWARE_SetClipping
00006440 T gcoHARDWARE_SetColorSource
000038d0 T gcoHARDWARE_SetDither2D
00006a54 T gcoHARDWARE_SetMonochromeSource
00003cc4 T gcoHARDWARE_SetMultiplyModes
00005cb4 T gcoHARDWARE_SetSource
00004430 T gcoHARDWARE_SetSourceColorKeyRange
0000454c T gcoHARDWARE_SetSourceGlobalColor
00004210 T gcoHARDWARE_SetStretchFactors
00004350 T gcoHARDWARE_SetSuperTileVersion
00005d70 T gcoHARDWARE_SetTarget
000044c0 T gcoHARDWARE_SetTargetColorKeyRange
000045ac T gcoHARDWARE_SetTargetGlobalColor
00004c70 T gcoHARDWARE_SetTransparencyModesEx
00003004 T gcoHARDWARE_StartDE
0000744c T gcoHARDWARE_StartDELine
000047a4 T gcoHARDWARE_TranslateAlphaFactorMode
00003bb8 T gcoHARDWARE_TranslateCommand
000061f0 T gcoHARDWARE_TranslateDestinationFormat
00006380 T gcoHARDWARE_TranslateDestinationRotation
00004f4c T gcoHARDWARE_TranslateDestinationTransparency
00004e78 T gcoHARDWARE_TranslateDFBColorKeyMode
00004a48 T gcoHARDWARE_TranslateGlobalAlphaMode
0000460c T gcoHARDWARE_TranslateGlobalColorMultiplyMode
00006994 T gcoHARDWARE_TranslateMonoPack
00005bd8 T gcoHARDWARE_TranslatePatternFormat
00004ed0 T gcoHARDWARE_TranslatePatternTransparency
00004ae8 T gcoHARDWARE_TranslatePixelAlphaMode
00004728 T gcoHARDWARE_TranslatePixelColorMode
000046ac T gcoHARDWARE_TranslatePixelColorMultiplyMode
000059b8 T gcoHARDWARE_TranslateSourceFormat
000068d4 T gcoHARDWARE_TranslateSourceRotation
00004fc8 T gcoHARDWARE_TranslateSourceTransparency
00005068 T gcoHARDWARE_TranslateTransparencies
         U n2d_allocate
00007cf8 T n2d_user_hardware_deinitialize
00007b1c T n2d_user_hardware_initialize
00002140 T n2d_user_hardware_load_2d_state
00000b58 T n2d_kernel_hardware_commit
0000070c T n2d_kernel_hardware_deinitialize
00000de0 T n2d_kernel_hardware_dump_gpu_state
00000af0 T n2d_kernel_hardware_end
00000730 T n2d_kernel_hardware_event
000003e4 T n2d_kernel_hardware_initialize
000009cc T n2d_kernel_hardware_link
00000a74 T n2d_kernel_hardware_nop
000002ac T n2d_kernel_hardware_query_chip_identity
000008d4 T n2d_kernel_hardware_wait_link
         U n2d_kernel_os_allocate_contiguous
         U n2d_kernel_os_delay
         U n2d_kernel_os_get_base_address
         U n2d_kernel_os_get_hardware_address
         U n2d_kernel_os_peek
         U n2d_kernel_os_poke
         U n2d_kernel_os_print
         U n2d_kernel_os_trace
         U n2d_kernel_os_wait_interrupt
         U n2d_kernel_hardware_initialize
00000000 T n2d_kernel_os_allocate
00000144 T n2d_kernel_os_allocate_contiguous
00000100 T n2d_kernel_os_delay
0000002c T n2d_kernel_os_free
000001a4 T n2d_kernel_os_free_contiguous
00000340 T n2d_kernel_os_get_base_address
000001d0 T n2d_kernel_os_get_hardware_address
0000020c T n2d_kernel_os_map
00000270 T n2d_kernel_os_peek
000002a8 T n2d_kernel_os_poke
0000039c T n2d_kernel_os_print
0000036c T n2d_kernel_os_trace
00000240 T n2d_kernel_os_unmap
000002e8 T n2d_kernel_os_wait_interrupt

[austriancoder]

After some minutes of googling I found one source telling that it is a gc200 - https://www.eejournal.com/article/add-glamour-to-your-product/

If Linux runs on add the needed DTS nodes for the GPU and it should work out-of-the-box.

Btw. we are a clean room reverse engineering project.

[ReimuNotMoe]

Thank you for the information. Because unlike all other peripherals, there are almost no information about this GPU in the datasheets, and Microchip staffs won't say a word about it.

I googled some etnaviv device tree snippets, and TBH I'm not very familiar with Linux DRM subsystem. Do I need to specify a memory location for framebuffer? Or the driver will allocate one in RAM automatically? Anyway I have to tell this memory location to the LCD controller (which is a separate peripheral) for the graphics to be actually displayed on screen.

Your project is awesome indeed.

[austriancoder]

Here is the dts binding: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/gpu/vivante,gc.yaml?h=v5.16-rc7

Here is one of many examples in the mainline linux kernel: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/imx6qdl.dtsi?h=v5.16-rc7#n215

Keep in mind that Vivnate GPUs are render-only GPUs and you need a KMS driver that does the actual scanout. So you do not need to specify a memory location for a framebuffer etc. If there is no KMS driver you can just use a simple test program to interact with the 2d GPU: https://cgit.freedesktop.org/mesa/drm/tree/tests/etnaviv/etnaviv_2d_test.c?h=main

[ReimuNotMoe]

Thank you very much for the information!