Differences

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--- irq_controller [2025/04/13 20:26] – arisotura
+++ irq_controller [2025/05/16 22:33] (current) – arisotura
@@ Line 91: / Line 91: @@
 Some IRQ sources will not function correctly without the correct trigger type. For example, VBlank IRQs will only fire once if their trigger type is set to 5.
+In practice, some IRQ lines likely stay active only for a very short time, while others will stay active as long as the underlying IRQ conditions are met (ie. from hardware components that have their own IRQ status registers; the IRQ line may stay active until the IRQ status register is cleared).
+IRQ trigger type 5 seems to fail to register an interrupt when the pulse is too short (ie. doesn't work for VBlank IRQ).
+The trigger type might also play a role in whether/how the IRQ line is buffered or treated? Values 0-7 are possible. Different values affect the different bits (8/12/13/14) in the IRQ enable registers. Some values don't work at all.
+Typically, it seems that 1 is used for IRQ sources that are "self-acknowledging" (ie. VBlank, timers, DMA, ...), and 5 is used for IRQ sources that need explicit acknowledgement (ie. SPI, I2C, audio, ...).
@@ Line 122: / Line 130: @@
 | 0x01      | 1       | Timer 1 |
 | 0x02      | 1       | SDIO |
-| 0x03      | 5       | ??? |
+| 0x03      | 5       | UART0 |
-| 0x04      | 5       | ??? |
+| 0x04      | 5       | UART1 |
-| 0x05      | 5       | UART |
+| 0x05      | 5       | UART2 |
 | 0x06      | 5       | SPI |
 | 0x07      | 5       | SPI related? |
@@ Line 136: / Line 144: @@
 | 0x0F      | 5       | I2C |
 | 0x10      | 5       | vcapt/camera |
-| 0x11      | 5       | vcapt/camera |
+| 0x11      | 5       | H264 encoder |
-| 0x12      | 5       | vout |
+| 0x12      | 5       | H264 decoder |
 | 0x13      | 5       | ??? |
-| 0x14      | 5       | vcapt/camera |
+| 0x14      | 5       | Camera controller |
 | 0x15      | 1       | VBlank end |
 | 0x16      | 1       | VBlank start |
@@ Line 155: / Line 163: @@
 | 0x22      | 1?      | ??? |
 | 0x23      | 1?      | ??? |
-| 0x24      | 1?      | ??? |
+| 0x24      | 1?      | ??? (video related, 0xF00094F8) |
 | 0x25      | 1?      | ??? |
-| 0x26      | 1?      | ??? |
+| 0x26      | 1?      | ??? (video related, 0xF000940C) |
 | 0x27      | 1?      | ??? |
+Note: trigger type for IRQ 0x02 is set to 1, which can cause a SDIO IRQ to be missed if it fires while another SDIO IRQ is being processed. Changing it to 5 fixes that problem. The stock firmware doesn't have that problem because it only uses the SDIO IRQ for the wifi card IRQ, and uses busy-loop polling to sense the end of SDIO transfers.
 IRQ 0x20..0x27 are actually FIQ sources. Not known what they're all about. Also unknown how to acknowledge a FIQ? Register 0xF00013F0 reads as 0x80 during a FIQ.
+The stock firmware doesn't use FIQs, and doesn't even have a FIQ handler (FIQ is redirected to the general exception handler).