Re: [PATCH v2 3/3] media: i2c: imx219: Scale the pixel rate for analog binning

Laurent Pinchart
2024-11-24T03:34:43Z

On Fri, Nov 22, 2024 at 11:31:58AM +0100, Jacopo Mondi wrote:
> On Thu, Nov 21, 2024 at 05:38:04PM +0530, Jai Luthra wrote:
> > When the analog binning mode is used for high framerate operation,
> > the pixel rate is effectively doubled. Account for this when setting up
> > the pixel clock rate, and applying the vblank and exposure controls.
> >
> > The previous logic only used analog binning for 8-bit modes, but normal
> > binning limits the framerate on 10-bit 480p [1]. So with this patch we
> > switch to using special binning (with 2x pixel rate) for all formats of
> > 480p mode and 8-bit 1232p.
> >
> > To do this cleanly, re-introduce the book-keeping for which binning mode
> > is used with which resolution/format.
>
> I think the patch is correct, however this goes a bit in the opposite
> direction of making the driver freely configurable. IOW the more we
> store in modes, the harder it will become to freely configure the
> sensor. I know there are different opinions on how much this is
> actually an issue, with valid arguments on both sides, but as I recall
> freely configurable was a goal of Laurent's series, let me cc him
> explicitly.

Correct. I would like the binning configuration to be computed by the
driver, not hardcoded. Let's do better than this.

> > [1]: https://github.com/raspberrypi/linux/issues/5493
> >
> > Co-developed-by: Naushir Patuck <naush@raspberrypi.com>
> > Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
> > Co-developed-by: Vinay Varma <varmavinaym@gmail.com>
> > Signed-off-by: Vinay Varma <varmavinaym@gmail.com>
> > Signed-off-by: Jai Luthra <jai.luthra@ideasonboard.com>
> > ---
> > drivers/media/i2c/imx219.c | 138 ++++++++++++++++++++++++++++++---------------
> > 1 file changed, 94 insertions(+), 44 deletions(-)
> >
> > diff --git a/drivers/media/i2c/imx219.c b/drivers/media/i2c/imx219.c
> > index 970e6362d0ae3a9078daf337155e83d637bc1ca1..ec795569361987ae30bff234e97fa34600bf5975 100644
> > --- a/drivers/media/i2c/imx219.c
> > +++ b/drivers/media/i2c/imx219.c
> > @@ -149,6 +149,18 @@
> > #define IMX219_PIXEL_ARRAY_WIDTH 3280U
> > #define IMX219_PIXEL_ARRAY_HEIGHT 2464U
> >
> > +enum binning_mode {
> > + BINNING_NONE = IMX219_BINNING_NONE,
> > + BINNING_X2 = IMX219_BINNING_X2,
> > + BINNING_ANALOG_X2 = IMX219_BINNING_X2_ANALOG,
> > +};
> > +
> > +enum binning_bit_depths {
> > + BINNING_IDX_8_BIT,
> > + BINNING_IDX_10_BIT,
> > + BINNING_IDX_MAX
> > +};
> > +
> > /* Mode : resolution and related config&values */
> > struct imx219_mode {
> > /* Frame width */
> > @@ -158,6 +170,9 @@ struct imx219_mode {
> >
> > /* V-timing */
> > unsigned int vts_def;
> > +
> > + /* binning mode based on format code */
> > + enum binning_mode binning[BINNING_IDX_MAX];
> > };
> >
> > static const struct cci_reg_sequence imx219_common_regs[] = {
> > @@ -293,24 +308,40 @@ static const struct imx219_mode supported_modes[] = {
> > .width = 3280,
> > .height = 2464,
> > .vts_def = 3526,
> > + .binning = {
> > + [BINNING_IDX_8_BIT] = BINNING_NONE,
> > + [BINNING_IDX_10_BIT] = BINNING_NONE,
> > + },
> > },
> > {
> > /* 1080P 30fps cropped */
> > .width = 1920,
> > .height = 1080,
> > .vts_def = 1763,
> > + .binning = {
> > + [BINNING_IDX_8_BIT] = BINNING_NONE,
> > + [BINNING_IDX_10_BIT] = BINNING_NONE,
> > + },
> > },
> > {
> > /* 2x2 binned 30fps mode */
> > .width = 1640,
> > .height = 1232,
> > .vts_def = 1763,
> > + .binning = {
> > + [BINNING_IDX_8_BIT] = BINNING_ANALOG_X2,
> > + [BINNING_IDX_10_BIT] = BINNING_X2,
> > + },
> > },
> > {
> > /* 640x480 30fps mode */
> > .width = 640,
> > .height = 480,
> > .vts_def = 1763,
> > + .binning = {
> > + [BINNING_IDX_8_BIT] = BINNING_ANALOG_X2,
> > + [BINNING_IDX_10_BIT] = BINNING_ANALOG_X2,
> > + },
> > },
> > };
> >
> > @@ -337,6 +368,9 @@ struct imx219 {
> >
> > /* Two or Four lanes */
> > u8 lanes;
> > +
> > + /* Binning mode */
> > + enum binning_mode binning;
> > };
> >
> > static inline struct imx219 *to_imx219(struct v4l2_subdev *_sd)
> > @@ -362,6 +396,36 @@ static u32 imx219_get_format_code(struct imx219 *imx219, u32 code)
> > return imx219_mbus_formats[i];
> > }
> >
> > +static u32 imx219_get_format_bpp(const struct v4l2_mbus_framefmt *format)
> > +{
> > + switch (format->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:
> > + return 8;
> > +
> > + case MEDIA_BUS_FMT_SRGGB10_1X10:
> > + case MEDIA_BUS_FMT_SGRBG10_1X10:
> > + case MEDIA_BUS_FMT_SGBRG10_1X10:
> > + case MEDIA_BUS_FMT_SBGGR10_1X10:
> > + default:
> > + return 10;
> > + }
> > +}
> > +
> > +static int imx219_get_rate_factor(struct imx219 *imx219)
> > +{
> > + switch (imx219->binning) {
> > + case BINNING_NONE:
> > + case BINNING_X2:
> > + return 1;
> > + case BINNING_ANALOG_X2:
> > + return 2;
> > + }
> > + return -EINVAL;
> > +}
> > +
> > /* -----------------------------------------------------------------------------
> > * Controls
> > */
> > @@ -373,10 +437,12 @@ static int imx219_set_ctrl(struct v4l2_ctrl *ctrl)
> > struct i2c_client *client = v4l2_get_subdevdata(&imx219->sd);
> > const struct v4l2_mbus_framefmt *format;
> > struct v4l2_subdev_state *state;
> > + int rate_factor;
> > int ret = 0;
> >
> > state = v4l2_subdev_get_locked_active_state(&imx219->sd);
> > format = v4l2_subdev_state_get_format(state, 0);
> > + rate_factor = imx219_get_rate_factor(imx219);
> >
> > if (ctrl->id == V4L2_CID_VBLANK) {
> > int exposure_max, exposure_def;
> > @@ -405,7 +471,7 @@ static int imx219_set_ctrl(struct v4l2_ctrl *ctrl)
> > break;
> > case V4L2_CID_EXPOSURE:
> > cci_write(imx219->regmap, IMX219_REG_EXPOSURE,
> > - ctrl->val, &ret);
> > + ctrl->val / rate_factor, &ret);
> > break;
> > case V4L2_CID_DIGITAL_GAIN:
> > cci_write(imx219->regmap, IMX219_REG_DIGITAL_GAIN,
> > @@ -422,7 +488,7 @@ static int imx219_set_ctrl(struct v4l2_ctrl *ctrl)
> > break;
> > case V4L2_CID_VBLANK:
> > cci_write(imx219->regmap, IMX219_REG_VTS,
> > - format->height + ctrl->val, &ret);
> > + (format->height + ctrl->val) / rate_factor, &ret);
> > break;
> > case V4L2_CID_HBLANK:
> > cci_write(imx219->regmap, IMX219_REG_HTS,
> > @@ -463,7 +529,8 @@ static const struct v4l2_ctrl_ops imx219_ctrl_ops = {
> >
> > static unsigned long imx219_get_pixel_rate(struct imx219 *imx219)
> > {
> > - return (imx219->lanes == 2) ? IMX219_PIXEL_RATE : IMX219_PIXEL_RATE_4LANE;
> > + return ((imx219->lanes == 2) ? IMX219_PIXEL_RATE :
> > + IMX219_PIXEL_RATE_4LANE) * imx219_get_rate_factor(imx219);
> > }
> >
> > /* Initialize control handlers */
> > @@ -592,29 +659,12 @@ static int imx219_set_framefmt(struct imx219 *imx219,
> > {
> > const struct v4l2_mbus_framefmt *format;
> > const struct v4l2_rect *crop;
> > - unsigned int bpp;
> > - u64 bin_h, bin_v;
> > + u32 bpp;
> > int ret = 0;
> >
> > format = v4l2_subdev_state_get_format(state, 0);
> > crop = v4l2_subdev_state_get_crop(state, 0);
> > -
> > - switch (format->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:
> > - bpp = 8;
> > - 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:
> > - default:
> > - bpp = 10;
> > - break;
> > - }
> > + bpp = imx219_get_format_bpp(format);
> >
> > cci_write(imx219->regmap, IMX219_REG_X_ADD_STA_A,
> > crop->left - IMX219_PIXEL_ARRAY_LEFT, &ret);
> > @@ -625,28 +675,8 @@ static int imx219_set_framefmt(struct imx219 *imx219,
> > cci_write(imx219->regmap, IMX219_REG_Y_ADD_END_A,
> > crop->top - IMX219_PIXEL_ARRAY_TOP + crop->height - 1, &ret);
> >
> > - switch (crop->width / format->width) {
> > - case 1:
> > - default:
> > - bin_h = IMX219_BINNING_NONE;
> > - break;
> > - case 2:
> > - bin_h = bpp == 8 ? IMX219_BINNING_X2_ANALOG : IMX219_BINNING_X2;
> > - break;
> > - }
> > -
> > - switch (crop->height / format->height) {
> > - case 1:
> > - default:
> > - bin_v = IMX219_BINNING_NONE;
> > - break;
> > - case 2:
> > - bin_v = bpp == 8 ? IMX219_BINNING_X2_ANALOG : IMX219_BINNING_X2;
>
> So if I got this right, another way of handling this would be to
>
> bin_v = (bpp == 8 || (format->width == 640 && format->height = 480)
> ? IMX219_BINNING_X2_ANALOG : IMX219_BINNING_X2;
>
>
> I'm not sure how much better this is, as then freely configure the
> sensor at (random numbers) 720x480@10bpp would not use analog binning
> while it might be beneficial. Actually knowing what analog mode is how
> it shuold be used would help, but if I recall correctly it wasn't
> clear from documentation or not fully clarified by Sony ?
>
> When it comes to scaling PIXEL_RATE, the above switch could be moved
> to set_pad_format and store imx219->binning to be
> 1) used here
> 2) used in s_ctrl
>
> like this patch does already.
>
> Opinions ?
>
> > - break;
> > - }
> > -
> > - cci_write(imx219->regmap, IMX219_REG_BINNING_MODE_H, bin_h, &ret);
> > - cci_write(imx219->regmap, IMX219_REG_BINNING_MODE_V, bin_v, &ret);
> > + cci_write(imx219->regmap, IMX219_REG_BINNING_MODE_H, imx219->binning, &ret);
> > + cci_write(imx219->regmap, IMX219_REG_BINNING_MODE_V, imx219->binning, &ret);
> >
> > cci_write(imx219->regmap, IMX219_REG_X_OUTPUT_SIZE,
> > format->width, &ret);
> > @@ -851,6 +881,21 @@ static int imx219_set_pad_format(struct v4l2_subdev *sd,
> > int exposure_max;
> > int exposure_def;
> > int hblank;
> > + int pixel_rate;
> > +
> > + /* Update binning mode based on format */
> > + switch (imx219_get_format_bpp(format)) {
> > + case 8:
> > + imx219->binning = mode->binning[BINNING_IDX_8_BIT];
> > + break;
> > +
> > + case 10:
> > + imx219->binning = mode->binning[BINNING_IDX_10_BIT];
> > + break;
> > +
> > + default:
> > + imx219->binning = BINNING_NONE;
> > + }
> >
> > /* Update limits and set FPS to default */
> > __v4l2_ctrl_modify_range(imx219->vblank, IMX219_VBLANK_MIN,
> > @@ -879,6 +924,11 @@ static int imx219_set_pad_format(struct v4l2_subdev *sd,
> > IMX219_PPL_MAX - mode->width,
> > 1, IMX219_PPL_MIN - mode->width);
> > __v4l2_ctrl_s_ctrl(imx219->hblank, hblank);
> > +
> > + /* Scale the pixel rate based on the mode specific factor */
> > + pixel_rate = imx219_get_pixel_rate(imx219);
> > + __v4l2_ctrl_modify_range(imx219->pixel_rate, pixel_rate,
> > + pixel_rate, 1, pixel_rate);
> > }
> >
> > return 0;

--
Regards,

Laurent Pinchart