Re: [RFC PATCH] media: rcar-csi2: Fix field detection

["Niklas Söderlund" <niklas.soderlund@ragnatech.se>]

Hi Steve,

On 2019-04-17 10:56:55 -0700, Steve Longerbeam wrote:
> Hi Nklas,
> 
> On 4/16/19 4:59 PM, Steve Longerbeam wrote:
> > Hi Niklas,
> > 
> > On 4/16/19 4:50 PM, Niklas Söderlund wrote:
> > > Hi Steve,
> > > 
> > > Thanks for your work.
> > > 
> > > I upported most rcar-csi2 patches but a few of them are still pending,
> > > an alternating version based on this BSP patch is already on its way.
> > > 
> > > https://patchwork.linuxtv.org/patch/55623/
> > 
> > Great, that patch confirms that FLD_NUM should be set to 0 or 1 when
> > setting FLD_DET_SEL = 0x01.
> > 
> > But your patch has it inverted. NTSC should be FLD_NUM=1, PAL should be
> > FLD_NUM=0. Can you please confirm that after reading the commit
> > description of my RFC patch.
> 
> Can you please confirm that your patch at
> https://patchwork.linuxtv.org/patch/55623 has the FLD_NUM bits inverted?
> It's the most important question regarding this. Please review my reasoning
> in the RFC patch. NTSC should be FLD_NUM=1, PAL should be FLD_NUM=0.

I think the patch is correct, in experiments the WC counter starts at 0 
not 1. I tested this by INTEN.INT_FSFE = 1 and then when the interrupt 
fires reading PH0M0 which contains WC in bits [23,8], DT in bits [7,6] 
and DT in bits [5,0].

PAL:
[   30.114552] rcar-csi2 fea80000.csi2: REG: 0x00012003
[   30.134481] rcar-csi2 fea80000.csi2: REG: 0x00011f03
0 (0) [-] interlaced 0 829440 B 30.135507 30.135898 12.000 fps ts mono/EoF
[   30.154548] rcar-csi2 fea80000.csi2: REG: 0x00012003
[   30.174477] rcar-csi2 fea80000.csi2: REG: 0x00011f03
1 (1) [-] interlaced 1 829440 B 30.175490 30.175571 25.011 fps ts mono/EoF
[   30.194542] rcar-csi2 fea80000.csi2: REG: 0x00012003
[   30.214472] rcar-csi2 fea80000.csi2: REG: 0x00011f03
2 (2) [-] interlaced 2 829440 B 30.215483 30.215569 25.004 fps ts mono/EoF
[   30.234535] rcar-csi2 fea80000.csi2: REG: 0x00012003
[   30.254466] rcar-csi2 fea80000.csi2: REG: 0x00011f03
3 (3) [-] interlaced 3 829440 B 30.255482 30.255569 25.001 fps ts mono/EoF
[   30.274531] rcar-csi2 fea80000.csi2: REG: 0x00012003
[   30.294459] rcar-csi2 fea80000.csi2: REG: 0x00011f03
4 (0) [-] interlaced 4 829440 B 30.295472 30.295544 25.006 fps ts mono/EoF
[   30.314525] rcar-csi2 fea80000.csi2: REG: 0x00012003
[   30.334454] rcar-csi2 fea80000.csi2: REG: 0x00011f03
5 (1) [-] interlaced 5 829440 B 30.335466 30.335545 25.004 fps ts mono/EoF
[   30.354519] rcar-csi2 fea80000.csi2: REG: 0x00012003
[   30.374450] rcar-csi2 fea80000.csi2: REG: 0x00011f03
6 (2) [-] interlaced 6 829440 B 30.375464 30.375540 25.001 fps ts mono/EoF
[   30.394515] rcar-csi2 fea80000.csi2: REG: 0x00012003
[   30.414443] rcar-csi2 fea80000.csi2: REG: 0x00011f03
7 (3) [-] interlaced 7 829440 B 30.415455 30.415535 25.006 fps ts mono/EoF
[   30.434508] rcar-csi2 fea80000.csi2: REG: 0x00012003
[   30.454438] rcar-csi2 fea80000.csi2: REG: 0x00011f03
8 (0) [-] interlaced 8 829440 B 30.455452 30.455528 25.002 fps ts mono/EoF
[   30.474503] rcar-csi2 fea80000.csi2: REG: 0x00012003
[   30.494433] rcar-csi2 fea80000.csi2: REG: 0x00011f03
9 (1) [-] interlaced 9 829440 B 30.495446 30.495519 25.004 fps ts mono/EoF

NTSC:
[   32.023281] rcar-csi2 fea80000.csi2: REG: 0x0001e503
[   32.039991] rcar-csi2 fea80000.csi2: REG: 0x0001e403
1 (1) [-] interlaced 1 691200 B 32.040883 32.040930 28.261 fps ts mono/EoF
[   32.056647] rcar-csi2 fea80000.csi2: REG: 0x0001e503
[   32.073358] rcar-csi2 fea80000.csi2: REG: 0x0001e403
2 (2) [-] interlaced 2 691200 B 32.074268 32.074336 29.954 fps ts mono/EoF
[   32.090015] rcar-csi2 fea80000.csi2: REG: 0x0001e503
[   32.106724] rcar-csi2 fea80000.csi2: REG: 0x0001e403
3 (3) [-] interlaced 3 691200 B 32.107634 32.107696 29.971 fps ts mono/EoF
[   32.123381] rcar-csi2 fea80000.csi2: REG: 0x0001e503
[   32.140092] rcar-csi2 fea80000.csi2: REG: 0x0001e403
4 (0) [-] interlaced 4 691200 B 32.140982 32.141024 29.987 fps ts mono/EoF
[   32.156747] rcar-csi2 fea80000.csi2: REG: 0x0001e503
[   32.173460] rcar-csi2 fea80000.csi2: REG: 0x0001e403
5 (1) [-] interlaced 5 691200 B 32.174354 32.174396 29.965 fps ts mono/EoF
[   32.190116] rcar-csi2 fea80000.csi2: REG: 0x0001e503
[   32.206827] rcar-csi2 fea80000.csi2: REG: 0x0001e403
6 (2) [-] interlaced 6 691200 B 32.207719 32.207759 29.972 fps ts mono/EoF
[   32.223485] rcar-csi2 fea80000.csi2: REG: 0x0001e503
[   32.240195] rcar-csi2 fea80000.csi2: REG: 0x0001e403
7 (3) [-] interlaced 7 691200 B 32.241101 32.241166 29.956 fps ts mono/EoF
[   32.256851] rcar-csi2 fea80000.csi2: REG: 0x0001e503
[   32.273563] rcar-csi2 fea80000.csi2: REG: 0x0001e403
8 (0) [-] interlaced 8 691200 B 32.274456 32.274497 29.981 fps ts mono/EoF
[   32.290218] rcar-csi2 fea80000.csi2: REG: 0x0001e503
[   32.306930] rcar-csi2 fea80000.csi2: REG: 0x0001e403
9 (1) [-] interlaced 9 691200 B 32.307823 32.307864 29.970 fps ts mono/EoF

I based my decision from this. If you have a other method to verify the 
behavior, contradicting results or think I interpreted the my data wrong 
I would be happy reconsider.

> 
> Also, slightly off-topic, but another question:
> 
> Do you know if it is possible to capture from a source that is sending
> SEQ-BT/TB and transfer to userspace as unmodified SEQ-BT/TB without
> requiring the capture of each field individually and concatenating them?
> 
> In other words, treat the frame from the source the same as progressive,
> i.e. as if the source were sending V4L2_FIELD_NONE. That is, program VnMC.IM
> bits as VNMC_IM_ODD_EVEN and use continuous frame capture mode.

I have very old patches [1] for this which I'm in the process of 
refreshing. This is one of the series which I hope to unblock by my 
upcoming cleanup of format handling inside rcar-vin.

If you plan to work on rcar-vin I would first like to get cleanup series 
in as I think it will be quiet intrusive. After that I plan to refresh 
all my VIN pending patches on top of that.

- V4L2_FIELD_SEQ_{TB,BT}
- Add support for UDS (Up Down Scaler)
- rcar-vin: add support for suspend and resume
- Reset register control
- Additional checks when starting (upported from BSP)

1. https://patchwork.linuxtv.org/patch/41742/

> 
> TIA,
> Steve
> 
> 
> > 
> > 
> > 
> > > 
> > > On 2019-04-16 16:38:07 -0700, Steve Longerbeam wrote:
> > > > The RCAR Gen3 hardware manual doesn't mention that the "Word
> > > > Count" field
> > > > in the MIPI CSI-2 Frame Start packet is really the frame number.
> > > > FS packets
> > > > are short packets, and short packets do not have a WC but rather
> > > > a 16-bit
> > > > data field, and for Frame synchronization packets (FS/FE) the
> > > > 16-bit data
> > > > field contains a frame number.
> > > > 
> > > > Here is a reprinting from the MIPI CSI-2 specification, version 2
> > > > (section 9.1.2 Low Level Protocol Short Packet Format):
> > > > 
> > > > "Figure 42 and Figure 43 show the Low Level Protocol Short Packet
> > > > structures for the D-PHY and C-PHY physical layer options,
> > > > respectively.
> > > > For each option, the Short Packet structure matches the Packet
> > > > Header of
> > > > the corresponding Low Level Protocol Long Packet structure with the
> > > > exception that the Packet Header Word Count (WC) field shall be
> > > > replaced
> > > > by the Short Packet Data Field...For Frame Synchronization Data Types
> > > > the Short Packet Data Field shall be the frame number..."
> > > > 
> > > > Also in section 9.8.1 Frame Synchronization Packets, the CSI-2
> > > > spec reads:
> > > > 
> > > > "The behavior of the 16-bit frame number shall be as one of the
> > > > following
> > > > - Frame number is always zero – frame number is inoperative.
> > > > - Frame number increments by 1 for every FS packet with the same
> > > > Virtual
> > > >    Channel and is periodically reset to one e.g. 1, 2, 1, 2, 1,
> > > > 2, 1, 2 or
> > > >    1, 2, 3, 4, 1, 2, 3, 4"
> > > > 
> > > > So from the above, FLD_NUM in the FLD register matches against the
> > > > frame number transmitted by the CSI-2 source in the Frame Start Packet,
> > > > and goes as "1,2,1,2,1,2" or "1,2,3,4,...,1,2,3,4". If there is
> > > > a match,
> > > > the RCAR CSI-2 receiver declares the field as the even, e.g. the
> > > > BOTTOM,
> > > > field.
> > > > 
> > > > NTSC transmits bottom/even field first, and PAL and HD transmit top/odd
> > > > field first. So fields with a frame number 1 in the CSI-2 Frame Start
> > > > Packet are bottom/even fields for NTSC, and frame number 2 are
> > > > bottom/even
> > > > fields for PAL/HD.
> > > > 
> > > > But the above assumes the transmitting CSI-2 sensor is sending frame
> > > > numbers in the sequence "1,2,1,2,...". But according to the CSI-2 spec,
> > > > sensors are also allowed to send frame numbers that simply increment as
> > > > in "1,2,3,4,...". To generalize to catch those cases, set FLD_DET_SEL
> > > > to 0x01, which according to the RCAR Gen3 hardware manual means "the
> > > > field is detected as the EVEN field when FLD_NUM[0] matches WC[0]".
> > > > Then, the even/bottom fields have odd frame numbers for NTSC, and even
> > > > frame numbers for PAL (this patch assumes HDMI sources will not
> > > > implement .g_std(), so std will be 0 in that case).
> > > > 
> > > > Finally, set the FLD register to non-zero value only if trnsmitter is
> > > > sending ALTERNATE fields.
> > > > 
> > > > Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com>
> > > > ---
> > > >   drivers/media/platform/rcar-vin/rcar-csi2.c | 37
> > > > ++++++++++++++++++---
> > > >   1 file changed, 32 insertions(+), 5 deletions(-)
> > > > 
> > > > diff --git a/drivers/media/platform/rcar-vin/rcar-csi2.c
> > > > b/drivers/media/platform/rcar-vin/rcar-csi2.c
> > > > index a438ec2c218f..c5bee20d7907 100644
> > > > --- a/drivers/media/platform/rcar-vin/rcar-csi2.c
> > > > +++ b/drivers/media/platform/rcar-vin/rcar-csi2.c
> > > > @@ -67,6 +67,7 @@ struct rcar_csi2;
> > > >   /* Field Detection Control */
> > > >   #define FLD_REG                0x1c
> > > >   #define FLD_FLD_NUM(n)            (((n) & 0xff) << 16)
> > > > +#define FLD_FLD_DET_SEL(n)        (((n) & 0x3) << 4)
> > > >   #define FLD_FLD_EN4            BIT(3)
> > > >   #define FLD_FLD_EN3            BIT(2)
> > > >   #define FLD_FLD_EN2            BIT(1)
> > > > @@ -462,10 +463,11 @@ static int rcsi2_calc_mbps(struct
> > > > rcar_csi2 *priv, unsigned int bpp)
> > > >       return mbps;
> > > >   }
> > > >   -static int rcsi2_start(struct rcar_csi2 *priv)
> > > > +static int rcsi2_start(struct rcar_csi2 *priv, struct
> > > > v4l2_subdev *nextsd)
> > > >   {
> > > >       const struct rcar_csi2_format *format;
> > > > -    u32 phycnt, vcdt = 0, vcdt2 = 0;
> > > > +    u32 phycnt, vcdt = 0, vcdt2 = 0, fld = 0;
> > > > +    v4l2_std_id std = 0;
> > > >       unsigned int i;
> > > >       int mbps, ret;
> > > >   @@ -476,6 +478,10 @@ static int rcsi2_start(struct rcar_csi2 *priv)
> > > >       /* Code is validated in set_fmt. */
> > > >       format = rcsi2_code_to_fmt(priv->mf.code);
> > > >   +    ret = v4l2_subdev_call(nextsd, video, g_std, &std);
> > > > +    if (ret < 0 && ret != -ENOIOCTLCMD && ret != -ENODEV)
> > > > +        return ret;
> > > > +
> > > >       /*
> > > >        * Enable all supported CSI-2 channels with virtual channel and
> > > >        * data type matching.
> > > > @@ -509,9 +515,30 @@ static int rcsi2_start(struct rcar_csi2 *priv)
> > > >       rcsi2_reset(priv);
> > > >       rcsi2_write(priv, PHTC_REG, 0);
> > > >   +    /*
> > > > +     * NTSC standard transmits even/bottom field first, then odd/top.
> > > > +     * PAL standard and interlaced HD transmit odd/top field first,
> > > > +     * then even/bottom.
> > > > +     *
> > > > +     * For CSI-2 sensors that transmit frame numbers (in the CSI-2
> > > > +     * Frame Start packet) as "1,2,1,2,..." or "1,2,3,4,5,...", then:
> > > > +     *
> > > > +     * - for NTSC, the even/bottom fields have odd frame numbers.
> > > > +     * - for PAL and HD, the even/bottom fields have even frame
> > > > numbers.
> > > > +     */
> > > > +    if (priv->mf.field == V4L2_FIELD_ALTERNATE) {
> > > > +        fld = FLD_FLD_DET_SEL(1) | FLD_FLD_EN4 | FLD_FLD_EN3 |
> > > > +            FLD_FLD_EN2 | FLD_FLD_EN;
> > > > +
> > > > +        if (std & V4L2_STD_525_60)
> > > > +            fld |= FLD_FLD_NUM(1); /* NTSC */
> > > > +        else
> > > > +            fld |= FLD_FLD_NUM(0); /* PAL or HD */
> > > > +    }
> > > > +
> > > >       /* Configure */
> > > > -    rcsi2_write(priv, FLD_REG, FLD_FLD_NUM(2) | FLD_FLD_EN4 |
> > > > -            FLD_FLD_EN3 | FLD_FLD_EN2 | FLD_FLD_EN);
> > > > +    rcsi2_write(priv, FLD_REG, fld);
> > > > +
> > > >       rcsi2_write(priv, VCDT_REG, vcdt);
> > > >       if (vcdt2)
> > > >           rcsi2_write(priv, VCDT2_REG, vcdt2);
> > > > @@ -591,7 +618,7 @@ static int rcsi2_s_stream(struct v4l2_subdev
> > > > *sd, int enable)
> > > >       if (enable && priv->stream_count == 0) {
> > > >           pm_runtime_get_sync(priv->dev);
> > > >   -        ret = rcsi2_start(priv);
> > > > +        ret = rcsi2_start(priv, nextsd);
> > > >           if (ret) {
> > > >               pm_runtime_put(priv->dev);
> > > >               goto out;
> > > > -- 
> > > > 2.17.1
> > > > 
> > 
> 

-- 
Regards,
Niklas Söderlund