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Message-ID: <maj7fvugwy25d4fny4km26yoed4o4zdggh3totbuatqu73qjs2@tllxhvjg7qey>
Date: Sun, 2 Nov 2025 12:07:55 +0100
From: Jacopo Mondi <jacopo.mondi@...asonboard.com>
To: Jai Luthra <jai.luthra@...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 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 :(
> 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..
> + 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...
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 ?
> 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
>
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