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Message-ID: <176346343076.268162.8926249825341031408@freya>
Date: Tue, 18 Nov 2025 16:27:10 +0530
From: Jai Luthra <jai.luthra@...asonboard.com>
To: Jacopo Mondi <jacopo.mondi@...asonboard.com>
Cc: Sakari Ailus <sakari.ailus@...ux.intel.com>, Dave Stevenson <dave.stevenson@...pberrypi.com>, Jacopo Mondi <jacopo@...ndi.org>, Mauro Carvalho Chehab <mchehab@...nel.org>, linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, Mauro Carvalho Chehab <mchehab+huawei@...nel.org>, Kieran Bingham <kieran.bingham@...asonboard.com>, David Plowman <david.plowman@...pberrypi.com>, Laurent Pinchart <laurent.pinchart@...asonboard.com>, Peter Robinson <pbrobinson@...il.com>, Stefan Wahren <wahrenst@....net>, Ivan T. Ivanov <iivanov@...e.de>
Subject: Re: [PATCH 09/13] media: i2c: ov5647: Add control of V4L2_CID_HBLANK
Hi Jacopo,
Thanks for the review.
Quoting Jacopo Mondi (2025-11-02 16:37:55)
> Hi Jai
>
> On Tue, Oct 28, 2025 at 12:57:20PM +0530, Jai Luthra wrote:
> > From: Dave Stevenson <dave.stevenson@...pberrypi.com>
> >
> > The driver did expose V4L2_CID_HBLANK, but as a READ_ONLY control.
> >
> > The sensor only uses the HTS register to control the line length,
> > so convert this control to read/write, with the appropriate ranges.
> > Adopt the old fixed values as the minimum values permitted in each
> > mode to avoid issues of it not streaming.
> >
> > This should allow exposure times up to ~3 seconds (up from ~1sec).
> >
> > Signed-off-by: Dave Stevenson <dave.stevenson@...pberrypi.com>
> > Signed-off-by: Jai Luthra <jai.luthra@...asonboard.com>
> > ---
> > drivers/media/i2c/ov5647.c | 26 +++++++++++++-------------
> > 1 file changed, 13 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/media/i2c/ov5647.c b/drivers/media/i2c/ov5647.c
> > index 3aad3dc9b5cd0c24c07a37e2567e3c61c52e4fc2..59c21b91d09d79f073a54871221f197a0bcf3aa2 100644
> > --- a/drivers/media/i2c/ov5647.c
> > +++ b/drivers/media/i2c/ov5647.c
> > @@ -53,6 +53,8 @@
> > #define OV5647_REG_AEC_AGC 0x3503
> > #define OV5647_REG_GAIN_HI 0x350a
> > #define OV5647_REG_GAIN_LO 0x350b
> > +#define OV5647_REG_HTS_HI 0x380c
> > +#define OV5647_REG_HTS_LO 0x380d
> > #define OV5647_REG_VTS_HI 0x380e
> > #define OV5647_REG_VTS_LO 0x380f
> > #define OV5647_REG_VFLIP 0x3820
> > @@ -79,6 +81,8 @@
> > #define OV5647_VBLANK_MIN 24
> > #define OV5647_VTS_MAX 32767
> >
> > +#define OV5647_HTS_MAX 0x1fff
> > +
> > #define OV5647_EXPOSURE_MIN 4
> > #define OV5647_EXPOSURE_STEP 1
> > #define OV5647_EXPOSURE_DEFAULT 1000
> > @@ -187,8 +191,6 @@ static struct regval_list ov5647_2592x1944_10bpp[] = {
> > {0x3a19, 0xf8},
> > {0x3c01, 0x80},
> > {0x3b07, 0x0c},
> > - {0x380c, 0x0b},
> > - {0x380d, 0x1c},
> > {0x3814, 0x11},
> > {0x3815, 0x11},
> > {0x3708, 0x64},
> > @@ -276,8 +278,6 @@ static struct regval_list ov5647_1080p30_10bpp[] = {
> > {0x3a19, 0xf8},
> > {0x3c01, 0x80},
> > {0x3b07, 0x0c},
> > - {0x380c, 0x09},
> > - {0x380d, 0x70},
> > {0x3814, 0x11},
> > {0x3815, 0x11},
> > {0x3708, 0x64},
> > @@ -375,8 +375,6 @@ static struct regval_list ov5647_2x2binned_10bpp[] = {
> > {0x3809, 0x10},
> > {0x380a, 0x03},
> > {0x380b, 0xcc},
> > - {0x380c, 0x07},
> > - {0x380d, 0x68},
> > {0x3811, 0x0c},
> > {0x3813, 0x06},
> > {0x3814, 0x31},
> > @@ -450,8 +448,6 @@ static struct regval_list ov5647_640x480_10bpp[] = {
> > {0x3a19, 0xf8},
> > {0x3c01, 0x80},
> > {0x3b07, 0x0c},
> > - {0x380c, 0x07},
> > - {0x380d, 0x3c},
> > {0x3814, 0x35},
> > {0x3815, 0x35},
> > {0x3708, 0x64},
> > @@ -1061,7 +1057,8 @@ static int ov5647_set_pad_fmt(struct v4l2_subdev *sd,
> > mode->pixel_rate, 1, mode->pixel_rate);
> >
> > hblank = mode->hts - mode->format.width;
> > - __v4l2_ctrl_modify_range(sensor->hblank, hblank, hblank, 1,
> > + __v4l2_ctrl_modify_range(sensor->hblank, hblank,
> > + OV5647_HTS_MAX - mode->format.width, 1,
>
> Is '1' really the min ? Who knows the datasheet doesn't report that :(
>
I think 1 is set as the step value here, keeping the minimum equal to
default HTS - width (to be safe, as I presume the HTS values for a mode
come from the sensor manufacturer)
> > hblank);
> >
> > vblank = mode->vts - mode->format.height;
> > @@ -1325,6 +1322,10 @@ static int ov5647_s_ctrl(struct v4l2_ctrl *ctrl)
> > ret = ov5647_write16(sd, OV5647_REG_VTS_HI,
> > sensor->mode->format.height + ctrl->val);
> > break;
> > + case V4L2_CID_HBLANK:
> > + ret = ov5647_write16(sd, OV5647_REG_HTS_HI,
> > + sensor->mode->format.width + ctrl->val);
>
> Why are we writing HTS_HI only ? The max control value is set to
> 0x1fff, this spans two registers..
>
IIUC ov5647_write16 sends two bytes of data over I2C, where it auto
increments the address when writing the second byte.
> > + break;
> > case V4L2_CID_TEST_PATTERN:
> > ret = ov5647_write(sd, OV5647_REG_ISPCTRL3D,
> > ov5647_test_pattern_val[ctrl->val]);
> > @@ -1332,7 +1333,6 @@ static int ov5647_s_ctrl(struct v4l2_ctrl *ctrl)
> >
> > /* Read-only, but we adjust it based on mode. */
> > case V4L2_CID_PIXEL_RATE:
> > - case V4L2_CID_HBLANK:
> > /* Read-only, but we adjust it based on mode. */
>
> We really like this comment, at the point of repeating it twice...
>
Oops, you're right, I'll drop this in the cleanup commit for PIXEL_RATE
control.
> Speaking of which... if you set the ctrl_handler to NULL when
> registering a ro control
>
> sensor->pixel_rate = v4l2_ctrl_new_std(&sensor->ctrls, NULL,
> V4L2_CID_PIXEL_RATE,
> sensor->mode->pixel_rate,
> sensor->mode->pixel_rate, 1,
> sensor->mode->pixel_rate);
>
> you can remove the above 4 lines.
>
> (the background is that for RO controls the control_handler has to be
> set to NULL, to avoid having to handle them in the s_ctrl handler)
>
> Maybe add a patch to this series ?
Nice, will do!
>
> > break;
> >
> > @@ -1409,10 +1409,11 @@ static int ov5647_init_controls(struct ov5647 *sensor, struct device *dev)
> > sensor->mode->pixel_rate, 1,
> > sensor->mode->pixel_rate);
> >
> > - /* By default, HBLANK is read only, but it does change per mode. */
> > hblank = sensor->mode->hts - sensor->mode->format.width;
> > sensor->hblank = v4l2_ctrl_new_std(&sensor->ctrls, &ov5647_ctrl_ops,
> > - V4L2_CID_HBLANK, hblank, hblank, 1,
> > + V4L2_CID_HBLANK, hblank,
> > + OV5647_HTS_MAX -
> > + sensor->mode->format.width, 1,
> > hblank);
> >
> > sensor->vblank = v4l2_ctrl_new_std(&sensor->ctrls, &ov5647_ctrl_ops,
> > @@ -1446,7 +1447,6 @@ static int ov5647_init_controls(struct ov5647 *sensor, struct device *dev)
> > goto handler_free;
> >
> > sensor->pixel_rate->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> > - sensor->hblank->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> > sensor->sd.ctrl_handler = &sensor->ctrls;
> >
> > return 0;
> >
> > --
> > 2.51.0
> >
Thanks,
Jai
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