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From:   "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
Date:   Tue, 3 Mar 2020 07:21:42 +0000
Message-ID: <CA+V-a8ue-V-x5wPTJYASTOanOV9kMJKtoxNHyhKWmHzyH-S-Pw@mail.gmail.com>
Subject: Re: [PATCH 2/3] media: i2c: imx219: Add support for SRGGB8_1X8 format
To:     Dave Stevenson <dave.stevenson@raspberrypi.com>
Cc:     Mauro Carvalho Chehab <mchehab@kernel.org>,
        Linux Media Mailing List <linux-media@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
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Sender: linux-kernel-owner@vger.kernel.org
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Hi Dave,

Thank you for the review.

On Mon, Mar 2, 2020 at 3:12 PM Dave Stevenson
<dave.stevenson@raspberrypi.com> wrote:
>
> Hi Lad.
>
> Thanks for the patch. A few things look wrong with it though.
>
> On Fri, 28 Feb 2020 at 16:55, Lad Prabhakar <prabhakar.csengg@gmail.com> wrote:
> >
> > imx219 sensor is capable for RAW8/RAW10 modes, this commit adds support
> > for SRGGB8_1X8 format.
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > ---
> >  drivers/media/i2c/imx219.c | 122 +++++++++++++++++++++++++++++--------
> >  1 file changed, 96 insertions(+), 26 deletions(-)
> >
> > diff --git a/drivers/media/i2c/imx219.c b/drivers/media/i2c/imx219.c
> > index 8b48e148f2d0..1388c9bc00bb 100644
> > --- a/drivers/media/i2c/imx219.c
> > +++ b/drivers/media/i2c/imx219.c
> > @@ -90,6 +90,9 @@
> >
> >  #define IMX219_REG_ORIENTATION         0x0172
> >
> > +#define IMX219_CSI_DATA_FORMAT_A_0_7   0x018c
> > +#define IMX219_CSI_DATA_FORMAT_A_8_15  0x018d
> > +
> >  /* Test Pattern Control */
> >  #define IMX219_REG_TEST_PATTERN                0x0600
> >  #define IMX219_TEST_PATTERN_DISABLE    0
> > @@ -135,6 +138,16 @@ struct imx219_mode {
> >         struct imx219_reg_list reg_list;
> >  };
> >
> > +struct imx219_pixfmt {
> > +       u32 code;
> > +       u32 colorspace;
> > +};
> > +
> > +static const struct imx219_pixfmt imx219_formats[] = {
> > +       { MEDIA_BUS_FMT_SRGGB8_1X8, V4L2_COLORSPACE_SRGB, },
> > +       { MEDIA_BUS_FMT_SRGGB10_1X10, V4L2_COLORSPACE_SRGB },
>
> Why do we need the colorspace here when they are both the same? I
> don't see any additional formats ever being added  as the sensor
> doesn't support them, so this seems redundant.
>
agreed will drop it.

> > +};
> > +
> >  /*
> >   * Register sets lifted off the i2C interface from the Raspberry Pi firmware
> >   * driver.
> > @@ -168,8 +181,6 @@ static const struct imx219_reg mode_3280x2464_regs[] = {
> >         {0x0171, 0x01},
> >         {0x0174, 0x00},
> >         {0x0175, 0x00},
> > -       {0x018c, 0x0a},
> > -       {0x018d, 0x0a},
> >         {0x0301, 0x05},
> >         {0x0303, 0x01},
> >         {0x0304, 0x03},
> > @@ -230,8 +241,6 @@ static const struct imx219_reg mode_1920_1080_regs[] = {
> >         {0x0171, 0x01},
> >         {0x0174, 0x00},
> >         {0x0175, 0x00},
> > -       {0x018c, 0x0a},
> > -       {0x018d, 0x0a},
> >         {0x0301, 0x05},
> >         {0x0303, 0x01},
> >         {0x0304, 0x03},
> > @@ -290,8 +299,6 @@ static const struct imx219_reg mode_1640_1232_regs[] = {
> >         {0x0171, 0x01},
> >         {0x0174, 0x01},
> >         {0x0175, 0x01},
> > -       {0x018c, 0x0a},
> > -       {0x018d, 0x0a},
> >         {0x0301, 0x05},
> >         {0x0303, 0x01},
> >         {0x0304, 0x03},
> >
> > @@ -413,6 +420,8 @@ struct imx219 {
> >         struct v4l2_subdev sd;
> >         struct media_pad pad;
> >
> > +       struct v4l2_mbus_framefmt fmt;
> > +
> >         struct clk *xclk; /* system clock to IMX219 */
> >         u32 xclk_freq;
> >
> > @@ -519,19 +528,26 @@ static int imx219_write_regs(struct imx219 *imx219,
> >  }
> >
> >  /* Get bayer order based on flip setting. */
> > -static u32 imx219_get_format_code(struct imx219 *imx219)
> > +static u32 imx219_get_format_code(struct imx219 *imx219, u32 code)
> >  {
> > -       /*
> > -        * Only one bayer order is supported.
> > -        * It depends on the flip settings.
> > -        */
> > -       static const u32 codes[2][2] = {
> > +       static const u32 codes10[2][2] = {
> >                 { MEDIA_BUS_FMT_SRGGB10_1X10, MEDIA_BUS_FMT_SGRBG10_1X10, },
> >                 { MEDIA_BUS_FMT_SGBRG10_1X10, MEDIA_BUS_FMT_SBGGR10_1X10, },
> >         };
> > +       static const u32 codes8[2][2] = {
> > +               { MEDIA_BUS_FMT_SRGGB8_1X8, MEDIA_BUS_FMT_SGRBG8_1X8, },
> > +               { MEDIA_BUS_FMT_SGBRG8_1X8, MEDIA_BUS_FMT_SBGGR8_1X8, },
> > +       };
> >
> >         lockdep_assert_held(&imx219->mutex);
> > -       return codes[imx219->vflip->val][imx219->hflip->val];
> > +
> > +       if (code == MEDIA_BUS_FMT_SRGGB10_1X10 ||
> > +           code == MEDIA_BUS_FMT_SGRBG10_1X10 ||
> > +           code == MEDIA_BUS_FMT_SGBRG10_1X10 ||
> > +           code == MEDIA_BUS_FMT_SBGGR10_1X10)
> > +               return codes10[imx219->vflip->val][imx219->hflip->val];
> > +
> > +       return codes8[imx219->vflip->val][imx219->hflip->val];
>
> Why defaulting to 8 bit? It's changing the behaviour for existing users.codes10
>
No it doesn't if, the format is set to 10-bit it shall look up from
codes10 and if its 8-bit
it does look from codes8.

> >  }
> >
> >  static int imx219_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
> > @@ -539,13 +555,26 @@ static int imx219_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
> >         struct imx219 *imx219 = to_imx219(sd);
> >         struct v4l2_mbus_framefmt *try_fmt =
> >                 v4l2_subdev_get_try_format(sd, fh->pad, 0);
> > +       struct v4l2_mbus_framefmt *fmt;
> >
> >         mutex_lock(&imx219->mutex);
> >
> > +       fmt = &imx219->fmt;
> > +       fmt->code = MEDIA_BUS_FMT_SRGGB8_1X8;
>
> Again, why defaulting to 8 bit? It's changing the behaviour for existing users.
>
agreed.

> > +       fmt->colorspace = V4L2_COLORSPACE_SRGB;
> > +       fmt->ycbcr_enc = V4L2_MAP_YCBCR_ENC_DEFAULT(fmt->colorspace);
> > +       fmt->quantization = V4L2_MAP_QUANTIZATION_DEFAULT(true,
> > +                                                         fmt->colorspace,
> > +                                                         fmt->ycbcr_enc);
> > +       fmt->xfer_func = V4L2_MAP_XFER_FUNC_DEFAULT(fmt->colorspace);
> > +       fmt->width = supported_modes[0].width;
> > +       fmt->height = supported_modes[0].height;
> > +       fmt->field = V4L2_FIELD_NONE;
> > +
> >         /* Initialize try_fmt */
> >         try_fmt->width = supported_modes[0].width;
> >         try_fmt->height = supported_modes[0].height;
> > -       try_fmt->code = imx219_get_format_code(imx219);
> > +       try_fmt->code = imx219_get_format_code(imx219, fmt->code);
> >         try_fmt->field = V4L2_FIELD_NONE;
> >
> >         mutex_unlock(&imx219->mutex);
> > @@ -646,16 +675,12 @@ static int imx219_enum_mbus_code(struct v4l2_subdev *sd,
> >                                  struct v4l2_subdev_pad_config *cfg,
> >                                  struct v4l2_subdev_mbus_code_enum *code)
> >  {
> > -       struct imx219 *imx219 = to_imx219(sd);
> > -
> > -       /*
> > -        * Only one bayer order is supported (though it depends on the flip
> > -        * settings)
> > -        */
> > -       if (code->index > 0)
> > +       if (code->pad != 0)
> > +               return -EINVAL;
> > +       if (code->index >= ARRAY_SIZE(imx219_formats))
> >                 return -EINVAL;
> >
> > -       code->code = imx219_get_format_code(imx219);
> > +       code->code = imx219_formats[code->index].code;
>
> This can't be right as it will only ever advertise
> MEDIA_BUS_FMT_SRGGB8_1X8 or MEDIA_BUS_FMT_SRGGB10_1X10, when the
> actual formats supported will change based on the H&V flips.
> MEDIA_BUS_FMT_SRGGB8_1X8. A caller therefore can't know the correct
> format should H or V flip be active, therefore can't set the right
> thing.
>
my understanding was the current driver implementation did the same it
just exposed
MEDIA_BUS_FMT_SRGGB10_1X10 and internally driver changed it
accordingly with flip settings.

> code->code = imx219_get_format_code(imx219, imx219_formats[code->index].code);
> would look more plausible.
>
> >         return 0;
> >  }
> > @@ -669,7 +694,7 @@ static int imx219_enum_frame_size(struct v4l2_subdev *sd,
> >         if (fse->index >= ARRAY_SIZE(supported_modes))
> >                 return -EINVAL;
> >
> > -       if (fse->code != imx219_get_format_code(imx219))
> > +       if (fse->code != imx219_get_format_code(imx219, imx219->fmt.code))
> >                 return -EINVAL;
> >
> >         fse->min_width = supported_modes[fse->index].width;
> > @@ -696,7 +721,7 @@ static void imx219_update_pad_format(struct imx219 *imx219,
> >  {
> >         fmt->format.width = mode->width;
> >         fmt->format.height = mode->height;
> > -       fmt->format.code = imx219_get_format_code(imx219);
> > +       fmt->format.code = imx219_get_format_code(imx219, imx219->fmt.code);
> >         fmt->format.field = V4L2_FIELD_NONE;
> >
> >         imx219_reset_colorspace(&fmt->format);
> > @@ -710,7 +735,7 @@ static int __imx219_get_pad_format(struct imx219 *imx219,
> >                 struct v4l2_mbus_framefmt *try_fmt =
> >                         v4l2_subdev_get_try_format(&imx219->sd, cfg, fmt->pad);
> >                 /* update the code which could change due to vflip or hflip: */
> > -               try_fmt->code = imx219_get_format_code(imx219);
> > +               try_fmt->code = imx219_get_format_code(imx219, try_fmt->code);
> >                 fmt->format = *try_fmt;
> >         } else {
> >                 imx219_update_pad_format(imx219, imx219->mode, fmt);
> > @@ -741,11 +766,19 @@ static int imx219_set_pad_format(struct v4l2_subdev *sd,
> >         const struct imx219_mode *mode;
> >         struct v4l2_mbus_framefmt *framefmt;
> >         int exposure_max, exposure_def, hblank;
> > +       int i;
> >
> >         mutex_lock(&imx219->mutex);
> >
> > +       for (i = 0; i < ARRAY_SIZE(imx219_formats); i++)
> > +               if (imx219_formats[i].code == fmt->format.code)
> > +                       break;
> > +       if (i >= ARRAY_SIZE(imx219_formats))
> > +               i = 0;
> > +
>
> Again, this doesn't take into account the H&V flips altering the Bayer
> format. If either are engaged then you can't change between 8 & 10 bit
> formats.
>
> It feels like having imx219_formats is the wrong approach.
> We already have all the formats available in a combination of codes8
> and codes10 (admittedly static to imx219_get_format_code). Is it
> better to make it into a single array where there is a strict
> requirement for the formats to be in the correct order of (eg) no
> flip, h flip, v flip, h&v flip. A lookup can then be a straight scan
> of the list. A correction for flip order is then index = (index & ~3)
> | (v_flip ? 2 : 0) | (h_flip ? 1 : 0);
>
Agreed that would make it more cleaner.

> >         /* Bayer order varies with flips */
> > -       fmt->format.code = imx219_get_format_code(imx219);
> > +       fmt->format.code = imx219_get_format_code(imx219,
> > +                                                 imx219_formats[i].code);
> >
> >         mode = v4l2_find_nearest_size(supported_modes,
> >                                       ARRAY_SIZE(supported_modes),
> > @@ -756,6 +789,7 @@ static int imx219_set_pad_format(struct v4l2_subdev *sd,
> >                 framefmt = v4l2_subdev_get_try_format(sd, cfg, fmt->pad);
> >                 *framefmt = fmt->format;
> >         } else if (imx219->mode != mode) {
> > +               imx219->fmt = fmt->format;
> >                 imx219->mode = mode;
> >                 /* Update limits and set FPS to default */
> >                 __v4l2_ctrl_modify_range(imx219->vblank, IMX219_VBLANK_MIN,
> > @@ -786,6 +820,36 @@ static int imx219_set_pad_format(struct v4l2_subdev *sd,
> >         return 0;
> >  }
> >
> > +static int imx219_set_framefmt(struct imx219 *imx219)
> > +{
> > +       int ret;
> > +
> > +       switch (imx219->fmt.code) {
> > +       case MEDIA_BUS_FMT_SRGGB8_1X8:
> > +       case MEDIA_BUS_FMT_SGRBG8_1X8:
> > +       case MEDIA_BUS_FMT_SGBRG8_1X8:
> > +       case MEDIA_BUS_FMT_SBGGR8_1X8:
> > +               ret = imx219_write_reg(imx219, IMX219_CSI_DATA_FORMAT_A_0_7,
> > +                                      IMX219_REG_VALUE_08BIT, 0x08);
> > +               ret |= imx219_write_reg(imx219, IMX219_CSI_DATA_FORMAT_A_8_15,
> > +                                      IMX219_REG_VALUE_08BIT, 0x08);
> > +               break;
> > +       case MEDIA_BUS_FMT_SRGGB10_1X10:
> > +       case MEDIA_BUS_FMT_SGRBG10_1X10:
> > +       case MEDIA_BUS_FMT_SGBRG10_1X10:
> > +       case MEDIA_BUS_FMT_SBGGR10_1X10:
> > +               ret = imx219_write_reg(imx219, IMX219_CSI_DATA_FORMAT_A_0_7,
> > +                                      IMX219_REG_VALUE_08BIT, 0x0a);
> > +               ret |= imx219_write_reg(imx219, IMX219_CSI_DATA_FORMAT_A_8_15,
> > +                                      IMX219_REG_VALUE_08BIT, 0x0a);
> > +               break;
>
> As just queried on your patch adding the 640x480 mode, do we not need
> to modify 0x0309 / OPPXCK_DIV to match the pixel format?
>
Yes.

> How do you propose handling matching pixel rate vs link frequency
> between the two modes?
> I'm seeing corrupted images, which probably implies the FIFO between
> "pipeline" and "MIPI" shown in Figure 43 of the datasheet is under or
> over flowing.
>
Ill do further investigation on it.

Cheers,
--Prabhakar

> > +       default:
> > +               ret = -EINVAL;
> > +       }
> > +
> > +       return ret;
> > +}
> > +
> >  static int imx219_start_streaming(struct imx219 *imx219)
> >  {
> >         struct i2c_client *client = v4l2_get_subdevdata(&imx219->sd);
> > @@ -800,6 +864,12 @@ static int imx219_start_streaming(struct imx219 *imx219)
> >                 return ret;
> >         }
> >
> > +       ret = imx219_set_framefmt(imx219);
> > +       if (ret) {
> > +               dev_err(&client->dev, "%s failed to set format\n", __func__);
> > +               return ret;
> > +       }
> > +
> >         /* Apply customized values from user */
> >         ret =  __v4l2_ctrl_handler_setup(imx219->sd.ctrl_handler);
> >         if (ret)
> > --
> > 2.20.1
> >