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PicoDVI/software/libdvi/dvi_timing.c

345 wiersze
12 KiB
C
Czysty Wina Historia

#include "dvi.h"
#include "dvi_timing.h"
#include "hardware/dma.h"
// This file contains:
// - Timing parameters for DVI modes (horizontal + vertical counts, best
// achievable bit clock from 12 MHz crystal)
// - Helper functions for generating DMA lists based on these timings
// Pull into RAM but apply unique section suffix to allow linker GC
#define __dvi_func(x) __not_in_flash_func(x)
#define __dvi_const(x) __not_in_flash_func(x)
// VGA -- we do this mode properly, with a pretty comfortable clk_sys (252 MHz)
const struct dvi_timing __dvi_const(dvi_timing_640x480p_60hz) = {
.h_sync_polarity = false,
.h_front_porch = 16,
.h_sync_width = 96,
.h_back_porch = 48,
.h_active_pixels = 640,
.v_sync_polarity = false,
.v_front_porch = 10,
.v_sync_width = 2,
.v_back_porch = 33,
.v_active_lines = 480,
.bit_clk_khz = 252000
};
// 720x480p 60 Hz -- Required by CEA for EDTV/HDTV displays. Convenient for
// emulating NTSC machines with visible overscan and reasonable clk_sys (270 MHz).
const struct dvi_timing __dvi_const(dvi_timing_720x480p_60hz) = {
.h_sync_polarity = false,
.h_front_porch = 16,
.h_sync_width = 62,
.h_back_porch = 60,
.h_active_pixels = 720,
.v_sync_polarity = false,
.v_front_porch = 9,
.v_sync_width = 6,
.v_back_porch = 30,
.v_active_lines = 480,
.bit_clk_khz = 270000
};
// SVGA -- completely by-the-book but requires 400 MHz clk_sys
const struct dvi_timing __dvi_const(dvi_timing_800x600p_60hz) = {
.h_sync_polarity = false,
.h_front_porch = 44,
.h_sync_width = 128,
.h_back_porch = 88,
.h_active_pixels = 800,
.v_sync_polarity = false,
.v_front_porch = 1,
.v_sync_width = 4,
.v_back_porch = 23,
.v_active_lines = 600,
.bit_clk_khz = 400000
};
// 800x480p 60 Hz (note this doesn't seem to be a CEA mode, I just used the
// output of `cvt 800 480 60`), 295 MHz bit clock
const struct dvi_timing __dvi_const(dvi_timing_800x480p_60hz) = {
.h_sync_polarity = false,
.h_front_porch = 24,
.h_sync_width = 72,
.h_back_porch = 96,
.h_active_pixels = 800,
.v_sync_polarity = true,
.v_front_porch = 3,
.v_sync_width = 10,
.v_back_porch = 7,
.v_active_lines = 480,
.bit_clk_khz = 295200
};
// SVGA reduced blanking (355 MHz bit clock) -- valid CVT mode, less common
// than fully-blanked SVGA, but doesn't require such a high system clock
const struct dvi_timing __dvi_const(dvi_timing_800x600p_reduced_60hz) = {
.h_sync_polarity = true,
.h_front_porch = 48,
.h_sync_width = 32,
.h_back_porch = 80,
.h_active_pixels = 800,
.v_sync_polarity = false,
.v_front_porch = 3,
.v_sync_width = 4,
.v_back_porch = 11,
.v_active_lines = 600,
.bit_clk_khz = 354000
};
// Also known as qHD, bit uncommon, but it's a nice modest-resolution 16:9
// aspect mode. Pixel clock 37.3 MHz
const struct dvi_timing __dvi_const(dvi_timing_960x540p_60hz) = {
.h_sync_polarity = true,
.h_front_porch = 16,
.h_sync_width = 32,
.h_back_porch = 96,
.h_active_pixels = 960,
.v_sync_polarity = true,
.v_front_porch = 2,
.v_sync_width = 6,
.v_back_porch = 15,
.v_active_lines = 540,
.bit_clk_khz = 372000
};
// Note this is NOT the correct 720p30 CEA mode, but rather 720p60 run at half
// pixel clock. Seems to be commonly accepted (and is a valid CVT mode). The
// actual CEA mode is the same pixel clock as 720p60 but with >50% blanking,
// which would require a clk_sys of 742 MHz!
const struct dvi_timing __dvi_const(dvi_timing_1280x720p_30hz) = {
.h_sync_polarity = true,
.h_front_porch = 110,
.h_sync_width = 40,
.h_back_porch = 220,
.h_active_pixels = 1280,
.v_sync_polarity = true,
.v_front_porch = 5,
.v_sync_width = 5,
.v_back_porch = 20,
.v_active_lines = 720,
.bit_clk_khz = 372000
};
// Reduced-blanking (CVT) 720p. You aren't supposed to use reduced blanking
// modes below 60 Hz, but I won't tell anyone (and it works on the monitors
// I've tried). This nets a lower system clock than regular 720p30 (319 MHz)
const struct dvi_timing __dvi_const(dvi_timing_1280x720p_reduced_30hz) = {
.h_sync_polarity = true,
.h_front_porch = 48,
.h_sync_width = 32,
.h_back_porch = 80,
.h_active_pixels = 1280,
.v_sync_polarity = false,
.v_front_porch = 3,
.v_sync_width = 5,
.v_back_porch = 13,
.v_active_lines = 720,
.bit_clk_khz = 319200
};
// This requires a spicy 488 MHz system clock and is illegal in most countries
// (you need to have a very lucky piece of silicon to run this at 1.3 V, or
// connect an external supply and give it a bit more juice)
const struct dvi_timing __dvi_const(dvi_timing_1600x900p_reduced_30hz) = {
.h_sync_polarity = true,
.h_front_porch = 48,
.h_sync_width = 32,
.h_back_porch = 80,
.h_active_pixels = 1600,
.v_sync_polarity = false,
.v_front_porch = 3,
.v_sync_width = 5,
.v_back_porch = 18,
.v_active_lines = 900,
.bit_clk_khz = 488000
};
// ----------------------------------------------------------------------------
// The DMA scheme is:
//
// - One channel transferring data to each of the three PIO state machines
// performing TMDS serialisation
//
// - One channel programming the registers of each of these data channels,
// triggered (CHAIN_TO) each time the corresponding data channel completes
//
// - Lanes 1 and 2 have one block for blanking and one for video data
//
// - Lane 0 has one block for each horizontal region (front porch, hsync, back
// porch, active)
//
// - The IRQ_QUIET flag is used to select which data block on the sync lane is
// allowed to generate an IRQ upon completion. This is the block immediately
// before the horizontal active region. The IRQ is entered at ~the same time
// as the last data transfer starts
//
// - The IRQ points the control channels at new blocklists for next scanline.
// The DMA starts the new list automatically at end-of-scanline, via
// CHAIN_TO.
//
// The horizontal active region is the longest continuous transfer, so this
// gives the most time to handle the IRQ and load new blocklists.
//
// Note a null trigger IRQ is not suitable because we get that *after* the
// last data transfer finishes, and the FIFOs bottom out very shortly
// afterward. For pure DVI (four blocks per scanline), it works ok to take
// four regular IRQs per scanline and return early from 3 of them, but this
// breaks down when you have very short scanline sections like guard bands.
// Each symbol appears twice, concatenated in one word. Note these must be in
// RAM because they see a lot of DMA traffic
const uint32_t __dvi_const(dvi_ctrl_syms)[4] = {
0xd5354,
0x2acab,
0x55154,
0xaaeab
};
// Output solid red scanline if we are given NULL for tmdsbuff
#if DVI_SYMBOLS_PER_WORD == 2
static uint32_t __dvi_const(empty_scanline_tmds)[3] = {
0x7fd00u, // 0x00, 0x00
0x7fd00u, // 0x00, 0x00
0xbfa01u // 0xfc, 0xfc
};
#else
static uint32_t __attribute__((aligned(8))) __dvi_const(empty_scanline_tmds)[6] = {
0x100u, 0x1ffu, // 0x00, 0x00
0x100u, 0x1ffu, // 0x00, 0x00
0x201u, 0x2feu // 0xfc, 0xfc
};
#endif
void dvi_timing_state_init(struct dvi_timing_state *t) {
t->v_ctr = 0;
t->v_state = DVI_STATE_FRONT_PORCH;
}
void __dvi_func(dvi_timing_state_advance)(const struct dvi_timing *t, struct dvi_timing_state *s) {
s->v_ctr++;
if ((s->v_state == DVI_STATE_FRONT_PORCH && s->v_ctr == t->v_front_porch) ||
(s->v_state == DVI_STATE_SYNC && s->v_ctr == t->v_sync_width) ||
(s->v_state == DVI_STATE_BACK_PORCH && s->v_ctr == t->v_back_porch) ||
(s->v_state == DVI_STATE_ACTIVE && s->v_ctr == t->v_active_lines)) {
s->v_state = (s->v_state + 1) % DVI_STATE_COUNT;
s->v_ctr = 0;
}
}
void dvi_scanline_dma_list_init(struct dvi_scanline_dma_list *dma_list) {
*dma_list = (struct dvi_scanline_dma_list){};
}
static const uint32_t *get_ctrl_sym(bool vsync, bool hsync) {
return &dvi_ctrl_syms[!!vsync << 1 | !!hsync];
}
// Make a sequence of paced transfers to the relevant FIFO
static void _set_data_cb(dma_cb_t *cb, const struct dvi_lane_dma_cfg *dma_cfg,
const void *read_addr, uint transfer_count, uint read_ring, bool irq_on_finish) {
cb->read_addr = read_addr;
cb->write_addr = dma_cfg->tx_fifo;
cb->transfer_count = transfer_count;
cb->c = dma_channel_get_default_config(dma_cfg->chan_data);
channel_config_set_ring(&cb->c, false, read_ring);
channel_config_set_dreq(&cb->c, dma_cfg->dreq);
// Call back to control channel for reconfiguration:
channel_config_set_chain_to(&cb->c, dma_cfg->chan_ctrl);
// Note we never send a null trigger, so IRQ_QUIET is an IRQ suppression flag
channel_config_set_irq_quiet(&cb->c, !irq_on_finish);
}
void dvi_setup_scanline_for_vblank(const struct dvi_timing *t, const struct dvi_lane_dma_cfg dma_cfg[],
bool vsync_asserted, struct dvi_scanline_dma_list *l) {
bool vsync = t->v_sync_polarity == vsync_asserted;
const uint32_t *sym_hsync_off = get_ctrl_sym(vsync, !t->h_sync_polarity);
const uint32_t *sym_hsync_on = get_ctrl_sym(vsync, t->h_sync_polarity);
const uint32_t *sym_no_sync = get_ctrl_sym(false, false );
dma_cb_t *synclist = dvi_lane_from_list(l, TMDS_SYNC_LANE);
// The symbol table contains each control symbol *twice*, concatenated into 20 LSBs of table word, so we can always do word-repeat.
_set_data_cb(&synclist[0], &dma_cfg[TMDS_SYNC_LANE], sym_hsync_off, t->h_front_porch / DVI_SYMBOLS_PER_WORD, 2, false);
_set_data_cb(&synclist[1], &dma_cfg[TMDS_SYNC_LANE], sym_hsync_on, t->h_sync_width / DVI_SYMBOLS_PER_WORD, 2, false);
_set_data_cb(&synclist[2], &dma_cfg[TMDS_SYNC_LANE], sym_hsync_off, t->h_back_porch / DVI_SYMBOLS_PER_WORD, 2, true);
_set_data_cb(&synclist[3], &dma_cfg[TMDS_SYNC_LANE], sym_hsync_off, t->h_active_pixels / DVI_SYMBOLS_PER_WORD, 2, false);
for (int i = 0; i < N_TMDS_LANES; ++i) {
if (i == TMDS_SYNC_LANE)
continue;
dma_cb_t *cblist = dvi_lane_from_list(l, i);
_set_data_cb(&cblist[0], &dma_cfg[i], sym_no_sync,(t->h_front_porch + t->h_sync_width + t->h_back_porch) / DVI_SYMBOLS_PER_WORD, 2, false);
_set_data_cb(&cblist[1], &dma_cfg[i], sym_no_sync, t->h_active_pixels / DVI_SYMBOLS_PER_WORD, 2, false);
}
}
void dvi_setup_scanline_for_active(const struct dvi_timing *t, const struct dvi_lane_dma_cfg dma_cfg[],
uint32_t *tmdsbuf, struct dvi_scanline_dma_list *l) {
const uint32_t *sym_hsync_off = get_ctrl_sym(!t->v_sync_polarity, !t->h_sync_polarity);
const uint32_t *sym_hsync_on = get_ctrl_sym(!t->v_sync_polarity, t->h_sync_polarity);
const uint32_t *sym_no_sync = get_ctrl_sym(false, false );
dma_cb_t *synclist = dvi_lane_from_list(l, TMDS_SYNC_LANE);
_set_data_cb(&synclist[0], &dma_cfg[TMDS_SYNC_LANE], sym_hsync_off, t->h_front_porch / DVI_SYMBOLS_PER_WORD, 2, false);
_set_data_cb(&synclist[1], &dma_cfg[TMDS_SYNC_LANE], sym_hsync_on, t->h_sync_width / DVI_SYMBOLS_PER_WORD, 2, false);
_set_data_cb(&synclist[2], &dma_cfg[TMDS_SYNC_LANE], sym_hsync_off, t->h_back_porch / DVI_SYMBOLS_PER_WORD, 2, true);
for (int i = 0; i < N_TMDS_LANES; ++i) {
dma_cb_t *cblist = dvi_lane_from_list(l, i);
if (i != TMDS_SYNC_LANE) {
_set_data_cb(&cblist[0], &dma_cfg[i], sym_no_sync,
(t->h_front_porch + t->h_sync_width + t->h_back_porch) / DVI_SYMBOLS_PER_WORD, 2, false);
}
int target_block = i == TMDS_SYNC_LANE ? DVI_SYNC_LANE_CHUNKS - 1 : DVI_NOSYNC_LANE_CHUNKS - 1;
if (tmdsbuf) {
// Non-repeating DMA for the freshly-encoded TMDS buffer
_set_data_cb(&cblist[target_block], &dma_cfg[i], tmdsbuf + i * (t->h_active_pixels / DVI_SYMBOLS_PER_WORD),
t->h_active_pixels / DVI_SYMBOLS_PER_WORD, 0, false);
}
else {
// Use read ring to repeat the correct DC-balanced symbol pair on blank scanlines (4 or 8 byte period)
_set_data_cb(&cblist[target_block], &dma_cfg[i], &empty_scanline_tmds[2 * i / DVI_SYMBOLS_PER_WORD],
t->h_active_pixels / DVI_SYMBOLS_PER_WORD, DVI_SYMBOLS_PER_WORD == 2 ? 2 : 3, false);
}
}
}
void __dvi_func(dvi_update_scanline_data_dma)(const struct dvi_timing *t, const uint32_t *tmdsbuf, struct dvi_scanline_dma_list *l) {
for (int i = 0; i < N_TMDS_LANES; ++i) {
#if DVI_MONOCHROME_TMDS
const uint32_t *lane_tmdsbuf = tmdsbuf;
#else
const uint32_t *lane_tmdsbuf = tmdsbuf + i * t->h_active_pixels / DVI_SYMBOLS_PER_WORD;
#endif
if (i == TMDS_SYNC_LANE)
dvi_lane_from_list(l, i)[3].read_addr = lane_tmdsbuf;
else
dvi_lane_from_list(l, i)[1].read_addr = lane_tmdsbuf;
}
}
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