GPU/External Registers
This page describes the address range used to configure the basic GPU functionality.
Map
| User VA | PA | Length | Name | Comments |
|---|---|---|---|---|
| 0x1EF00004 | 0x10400004 | 4 | ? | |
| 0x1EF00010 | 0x10400010 | 16 | Memory Fill1 "PSC0" | GX command 2 |
| 0x1EF00020 | 0x10400020 | 16 | Memory Fill2 "PSC1" | GX command 2 |
| 0x1EF00030 | 0x10400030 | 4 | ? | |
| 0x1EF00034 | 0x10400034 | 4 | GPU Busy | Bit31 = cmd-list busy, bit27 = PSC0 busy, bit26 = PSC1 busy. |
| 0x1EF00400 | 0x10400400 | 0x100 | Framebuffer Setup "PDC0" (top screen) | |
| 0x1EF00500 | 0x10400500 | 0x100 | Framebuffer Setup "PDC1" (bottom) | |
| 0x1EF00C00 | 0x10400C00 | ? | Transfer Engine "DMA" | |
| 0x1EF014?? | 0x104014?? | 0x14 | PPF | |
| 0x1EF018E0 | 0x104018E0 | 0x14 | Command List "P3D" |
Memory Fill
| User VA | Description |
|---|---|
| 0x1EF000X0 | Buffer start physaddr >> 3 |
| 0x1EF000X4 | Buffer end physaddr >> 3 |
| 0x1EF000X8 | Fill value |
| 0x1EF000XC | Control. bit0: start/busy, bit1: finished, bit8-9: fill-width (0=16bit, 1=3=24bit, 2=32bit) |
Memory fills are used to initialize buffers in memory with a given value, similar to memset. A memory fill is triggered by setting bit0 in the control register. Doing so aborts any running memory fills on that filling unit.
These registers are used by GX SetMemoryFill.
Framebuffer Setup
| Offset | Length | Name | Comments |
|---|---|---|---|
| 0x5C | 4 | Framebuffer width & height | Lower 16 bits: width, upper 16 bits: height |
| 0x68 | 4 | Framebuffer A first address | For top screen, this is the left eye 3D framebuffer. |
| 0x6C | 4 | Framebuffer A second address | For top screen, this is the left eye 3D framebuffer. |
| 0x70 | 4 | Framebuffer format | Bit0-15: framebuffer format, bit16-31: unknown |
| 0x78 | 4 | Framebuffer select | Bit0: which framebuffer to display, bit1-7: unknown |
| 0x90 | 4 | Framebuffer size | Framebuffer width * pixel byte-size. |
| 0x94 | 4 | Framebuffer B first address | For top screen, this is the right eye 3D framebuffer. Unused for bottom screen. |
| 0x98 | 4 | Framebuffer B second address | For top screen, this is the right eye 3D framebuffer. Unused for bottom screen. |
Framebuffer format
| Bit | Description |
|---|---|
| 2-0 | Color format |
| 3 | ? |
| 4 | Unused? |
| 5 | Set when the main screen 3D right framebuffer address is set. |
| 6 | 1 = main screen, 0 = sub screen. However if bit5 is set, this bit is cleared. |
| 7 | ? |
| 9-8 | Value 1 = unknown: get rid of rainbow strip on top of screen, 3 = unknown: black screen. |
| 15-10 | Unused? |
GSP module only allows the LCD stereoscopy to be enabled when bit5=1 and bit6=0 here. When GSP module updates this register, GSP module will automatically disable the stereoscopy if those bits are not set for enabling stereoscopy.
Framebuffer color formats
| Value | Description | Actual color components ordering |
|---|---|---|
| 0 | GL_RGBA8_OES | |
| 1 | GL_RGB8_OES | BGR |
| 2 | GL_RGB565_OES | RGB |
| 3 | GL_RGB5_A1_OES | |
| 4 | GL_RGBA4_OES |
Transfer Engine
| Register address | Description |
|---|---|
| 0x1EF00C00 | Input physical address>>3 |
| 0x1EF00C04 | Output physical address>>3 |
| 0x1EF00C08 | Output framebuffer dimensions, used with cmd3 |
| 0x1EF00C0C | Input framebuffer dimensions, used with cmd3 |
| 0x1EF00C10 | Flags, used with cmd3 and cmd4. |
| 0x1EF00C14 | GSP module writes value 0 here prior to writing to 0x1EF00C18, for cmd3. |
| 0x1EF00C18 | Setting bit0 starts the DMA transfer. |
| 0x1EF00C20 | Unknown, used with cmd4 |
| 0x1EF00C24 | Unknown, used with cmd4 |
| 0x1EF00C28 | Unknown, used with cmd4 |
These registers are used by GX command 3 and 4. For cmd4, *0x1EF00C18 |= 1 is used instead of just writing value 1. The dimensions fields seem to use the same format as LCD register 0x1EF00X5C. The input framebuffer width for the main screen is normally 480.
0x1EF00C10
| Bit | Description |
|---|---|
| 0 | When set, the framebuffer data is flipped vertically.(Normally zero) |
| 1 | When set, the framebuffer data is converted to tiles. (Normally zero) |
| 2 | This bit is set when the out-framebuf width/height is less than the input framebuf width/height, clear otherwise. Bit24 is normally clear when this bit is set. |
| 3 | When set, the framebuffer data is copied linearly, without doing any conversion (by default it is converted from tiles to linear). This has priority over bit1. |
| 4 | Unused |
| 5 | Unknown, normally zero. |
| 7-6 | Unused |
| 10-8 | Input framebuffer color format, value0 and value1 are the same as the LCD framebuffer formats.(Usually zero) |
| 11 | Unused |
| 14-12 | Output framebuffer color format |
| 15 | Unused |
| 16 | When this is set, the framebuffer data is converted to tiles.(Normally zero) |
| 19-17 | Unused |
| 21-20 | Unknown, output framebuffer data doesn't seem to change when this value is changed.(Normally zero) |
| 23-22 | Unused |
| 24 | This is set when the input_framebufwidth = output_framebufwidth<<1. |
| 31-25 | Unused |
Command List
| Register address | Description |
|---|---|
| 0x1EF018E0 | Buffer size >> 3 |
| 0x1EF018E8 | Buffer physical address >> 3 |
| 0x1EF018F0 | Writing value 1 here triggers GPU to execute the commands. |
These 3 registers are used by GX command 1. This is used for GPU commands.
Framebuffers
These LCD framebuffers normally contain the last rendered frames from the GPU. The framebuffers are drawn from left-to-right, instead of top-to-bottom.(Thus the beginning of the framebuffer is drawn starting at the left side of the screen)
Both of the 3D screen left/right framebuffers are displayed regardless of the 3D slider's state, however when the 3D slider is set to "off" the 3D effect is disabled. Normally when the 3D slider's state is set to "off" the left/right framebuffer addresses are set to the same physical address. When the 3D effect is disabled and the left/right framebuffers are set to separate addresses, the LCD seems to alternate between displaying the left/right framebuffer each frame.
Init Values from nngxInitialize for Top Screen
- 0x1EF00400 = 0x1C2
- 0x1EF00404 = 0xD1
- 0x1EF00408 = 0x1C1
- 0x1EF0040C = 0x1C1
- 0x1EF00410 = 0
- 0x1EF00414 = 0xCF
- 0x1EF00418 = 0xD1
- 0x1EF0041C = 0x1C501C1
- 0x1EF00420 = 0x10000
- 0x1EF00424 = 0x19D
- 0x1EF00428 = 2
- 0x1EF0042C = 0x1C2
- 0x1EF00430 = 0x1C2
- 0x1EF00434 = 0x1C2
- 0x1EF00438 = 1
- 0x1EF0043C = 2
- 0x1EF00440 = 0x1960192
- 0x1EF00444 = 0
- 0x1EF00448 = 0
- 0x1EF0045C = 0x19000F0
- 0x1EF00460 = 0x1c100d1
- 0x1EF00464 = 0x1920002
- 0x1EF00470 = 0x80340
- 0x1EF0049C = 0
More Init Values from nngxInitialize for Top Screen
- 0x1EF00468 = 0x18300000, later changed by GSP module when updating state, framebuffer
- 0x1EF0046C = 0x18300000, later changed by GSP module when updating state, framebuffer
- 0x1EF00494 = 0x18300000
- 0x1EF00498 = 0x18300000
- 0x1EF00478 = 1, doesn't stay 1, read as 0
- 0x1EF00474 = 0x10501