[PATCH v2 REPOST] TDA1997x: replace video detection routine

From: Krzysztof Hałasa
Date: Wed Oct 06 2021 - 01:30:24 EST

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The TDA1997x (HDMI receiver) driver currently uses a specific video
format detection scheme. The frame (or field in interlaced mode), line
and HSync pulse durations are compared to those of known, standard video
modes. If a match is found, the mode is assumed to be detected,
otherwise -ERANGE is returned (then possibly ignored). This means that:
- another mode with similar timings will be detected incorrectly
(e.g. 2x faster clock and lines twice as long)
- non-standard modes will not work.

This patch replaces this scheme with a direct read of geometry
registers. This way all modes recognized by the chip are supported.

In interlaced modes, the code assumes the V sync signal has the same
duration for both fields. While this may be not necessarily true,
I can't see any way to get the "other" V sync width. This is most
probably harmless.

All tests have been performed on Gateworks' Ventana GW54xx board, with
a TDA19971 chip.

Signed-off-by: Krzysztof Hałasa <khalasa@xxxxxxx>
Tested-By: Tim Harvey <tharvey@xxxxxxxxxxxxx>

---
This version extracts H and V sync polarities of the incoming signal and
matches the parameters against the standard video modes.

1/1000 pixel clock tolerance had to be increased to 1/500 because the
1/1.001 (NTSC-like) pixclk and frame rate reduction already caused
1/1000 deviation, and there was no room for further difference.

diff --git a/drivers/media/i2c/tda1997x.c b/drivers/media/i2c/tda1997x.c
index e155d45ce658..d62873cb9d45 100644
--- a/drivers/media/i2c/tda1997x.c
+++ b/drivers/media/i2c/tda1997x.c
@@ -1092,67 +1092,82 @@ tda1997x_detect_std(struct tda1997x_state *state,
struct v4l2_dv_timings *timings)
{
struct v4l2_subdev *sd = &state->sd;
- u32 vper;
- u16 hper;
- u16 hsper;
- int i;

/*
* Read the FMT registers
- * REG_V_PER: Period of a frame (or two fields) in MCLK(27MHz) cycles
- * REG_H_PER: Period of a line in MCLK(27MHz) cycles
- * REG_HS_WIDTH: Period of horiz sync pulse in MCLK(27MHz) cycles
+ * REG_V_PER: Period of a frame (or field) in MCLK (27MHz) cycles
+ * REG_H_PER: Period of a line in MCLK (27MHz) cycles
+ * REG_HS_WIDTH: Period of horiz sync pulse in MCLK (27MHz) cycles
*/
- vper = io_read24(sd, REG_V_PER) & MASK_VPER;
- hper = io_read16(sd, REG_H_PER) & MASK_HPER;
- hsper = io_read16(sd, REG_HS_WIDTH) & MASK_HSWIDTH;
- v4l2_dbg(1, debug, sd, "Signal Timings: %u/%u/%u\n", vper, hper, hsper);
+ u32 vper, vsync_pos;
+ u16 hper, hsync_pos, hsper, interlaced;
+ u16 htot, hact, hfront, hsync, hback;
+ u16 vtot, vact, vfront1, vfront2, vsync, vback1, vback2;

if (!state->input_detect[0] && !state->input_detect[1])
return -ENOLINK;

- for (i = 0; v4l2_dv_timings_presets[i].bt.width; i++) {
- const struct v4l2_bt_timings *bt;
- u32 lines, width, _hper, _hsper;
- u32 vmin, vmax, hmin, hmax, hsmin, hsmax;
- bool vmatch, hmatch, hsmatch;
-
- bt = &v4l2_dv_timings_presets[i].bt;
- width = V4L2_DV_BT_FRAME_WIDTH(bt);
- lines = V4L2_DV_BT_FRAME_HEIGHT(bt);
- _hper = (u32)bt->pixelclock / width;
- if (bt->interlaced)
- lines /= 2;
- /* vper +/- 0.7% */
- vmin = ((27000000 / 1000) * 993) / _hper * lines;
- vmax = ((27000000 / 1000) * 1007) / _hper * lines;
- /* hper +/- 1.0% */
- hmin = ((27000000 / 100) * 99) / _hper;
- hmax = ((27000000 / 100) * 101) / _hper;
- /* hsper +/- 2 (take care to avoid 32bit overflow) */
- _hsper = 27000 * bt->hsync / ((u32)bt->pixelclock/1000);
- hsmin = _hsper - 2;
- hsmax = _hsper + 2;
-
- /* vmatch matches the framerate */
- vmatch = ((vper <= vmax) && (vper >= vmin)) ? 1 : 0;
- /* hmatch matches the width */
- hmatch = ((hper <= hmax) && (hper >= hmin)) ? 1 : 0;
- /* hsmatch matches the hswidth */
- hsmatch = ((hsper <= hsmax) && (hsper >= hsmin)) ? 1 : 0;
- if (hmatch && vmatch && hsmatch) {
- v4l2_print_dv_timings(sd->name, "Detected format: ",
- &v4l2_dv_timings_presets[i],
- false);
- if (timings)
- *timings = v4l2_dv_timings_presets[i];
- return 0;
- }
- }
+ vper = io_read24(sd, REG_V_PER);
+ hper = io_read16(sd, REG_H_PER);
+ hsper = io_read16(sd, REG_HS_WIDTH);
+ vsync_pos = vper & MASK_VPER_SYNC_POS;
+ hsync_pos = hper & MASK_HPER_SYNC_POS;
+ interlaced = hsper & MASK_HSWIDTH_INTERLACED;
+ vper &= MASK_VPER;
+ hper &= MASK_HPER;
+ hsper &= MASK_HSWIDTH;
+ v4l2_dbg(1, debug, sd, "Signal Timings: %u/%u/%u\n", vper, hper, hsper);

- v4l_err(state->client, "no resolution match for timings: %d/%d/%d\n",
- vper, hper, hsper);
- return -ERANGE;
+ htot = io_read16(sd, REG_FMT_H_TOT);
+ hact = io_read16(sd, REG_FMT_H_ACT);
+ hfront = io_read16(sd, REG_FMT_H_FRONT);
+ hsync = io_read16(sd, REG_FMT_H_SYNC);
+ hback = io_read16(sd, REG_FMT_H_BACK);
+
+ vtot = io_read16(sd, REG_FMT_V_TOT);
+ vact = io_read16(sd, REG_FMT_V_ACT);
+ vfront1 = io_read(sd, REG_FMT_V_FRONT_F1);
+ vfront2 = io_read(sd, REG_FMT_V_FRONT_F2);
+ vsync = io_read(sd, REG_FMT_V_SYNC);
+ vback1 = io_read(sd, REG_FMT_V_BACK_F1);
+ vback2 = io_read(sd, REG_FMT_V_BACK_F2);
+
+ v4l2_dbg(1, debug, sd, "Geometry: H %u %u %u %u %u Sync%c V %u %u %u %u %u %u %u Sync%c\n",
+ htot, hact, hfront, hsync, hback, hsync_pos ? '+' : '-',
+ vtot, vact, vfront1, vfront2, vsync, vback1, vback2, vsync_pos ? '+' : '-');
+
+ if (!timings)
+ return 0;
+
+ timings->type = V4L2_DV_BT_656_1120;
+ timings->bt.width = hact;
+ timings->bt.hfrontporch = hfront;
+ timings->bt.hsync = hsync;
+ timings->bt.hbackporch = hback;
+ timings->bt.height = vact;
+ timings->bt.vfrontporch = vfront1;
+ timings->bt.vsync = vsync;
+ timings->bt.vbackporch = vback1;
+ timings->bt.interlaced = interlaced ? V4L2_DV_INTERLACED : V4L2_DV_PROGRESSIVE;
+ timings->bt.polarities = vsync_pos ? V4L2_DV_VSYNC_POS_POL : 0;
+ timings->bt.polarities |= hsync_pos ? V4L2_DV_HSYNC_POS_POL : 0;
+
+ timings->bt.pixelclock = (u64)htot * vtot * 27000000;
+ if (interlaced) {
+ timings->bt.il_vfrontporch = vfront2;
+ timings->bt.il_vsync = timings->bt.vsync;
+ timings->bt.il_vbackporch = vback2;
+ do_div(timings->bt.pixelclock, vper * 2 /* full frame */);
+ } else {
+ timings->bt.il_vfrontporch = 0;
+ timings->bt.il_vsync = 0;
+ timings->bt.il_vbackporch = 0;
+ do_div(timings->bt.pixelclock, vper);
+ }
+ v4l2_find_dv_timings_cap(timings, &tda1997x_dv_timings_cap,
+ (u32)timings->bt.pixelclock / 500, NULL, NULL);
+ v4l2_print_dv_timings(sd->name, "Detected format: ", timings, false);
+ return 0;
}

/* some sort of errata workaround for chip revision 0 (N1) */
diff --git a/drivers/media/i2c/tda1997x_regs.h b/drivers/media/i2c/tda1997x_regs.h
index d9b3daada07d..115371ba33f0 100644
--- a/drivers/media/i2c/tda1997x_regs.h
+++ b/drivers/media/i2c/tda1997x_regs.h
@@ -117,9 +117,12 @@
#define REG_CURPAGE_00H 0xFF

#define MASK_VPER 0x3fffff
+#define MASK_VPER_SYNC_POS 0x800000
#define MASK_VHREF 0x3fff
#define MASK_HPER 0x0fff
+#define MASK_HPER_SYNC_POS 0x8000
#define MASK_HSWIDTH 0x03ff
+#define MASK_HSWIDTH_INTERLACED 0x8000

/* HPD Detection */
#define DETECT_UTIL BIT(7) /* utility of HDMI level */

--
Krzysztof "Chris" Hałasa

Sieć Badawcza Łukasiewicz
Przemysłowy Instytut Automatyki i Pomiarów PIAP
Al. Jerozolimskie 202, 02-486 Warszawa

Next message: Vinod Koul: "Re: [Freedreno] [PATCH 02/11] drm/msm/disp/dpu1: Add support for DSC"
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