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Date: Thu, 19 Aug 2021 16:51:53 -0700
From: Tim Harvey <tharvey@...eworks.com>
To: Krzysztof Hałasa <khalasa@...p.pl>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
linux-media <linux-media@...r.kernel.org>,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] TDA1997x: replace video detection routine
On Thu, Aug 19, 2021 at 12:52 PM Tim Harvey <tharvey@...eworks.com> wrote:
>
> On Mon, Jul 26, 2021 at 4:01 AM Krzysztof Hałasa <khalasa@...p.pl> wrote:
> >
> > 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.
> >
> > I propose to replace this scheme with a direct read of geometry
> > registers. This way all modes recognized by the chip will be 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.
> >
> > I have checked the register values in interlaced mode, but currently
> > can't test such a setup (I only have remote access to a device working
> > in interlaced mode). Perhaps this will change in time.
> >
> > All tests have been performed on Gateworks' Ventana GW54xx board, with
> > a TDA19971 chip.
> >
> > Signed-off-by: Krzysztof Hałasa <khalasa@...p.pl>
> >
> > ---
> > 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.
> >
> > This patch requires just posted "[PATCH] TDA1997x: report -ENOLINK
> > after disconnecting HDMI source".
> >
> > diff --git a/drivers/media/i2c/tda1997x.c b/drivers/media/i2c/tda1997x.c
> > index 36a7b89afb08..a6afb387785d 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,
>
> I can't get this to apply (to 5.13, linux/master, or
> linux-media/master). What are you based on and do you have a git repo
> I can get it from?
>
Krzysztof,
My mistake - I was trying to apply your original patch. I was able to
successfully test this on GW5404-G with several HDMI input formats.
Tested-By: Tim Harvey <tharvey@...eworks.com>
Thanks, this is a great improvement!
Best regards,
Tim
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