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Message-ID: <j4t7zyhf4zhn5t27os7yxi3chaux3m6bjlxe774crmdmzzm54f@dlk5s5ai7ehc>
Date: Wed, 3 Sep 2025 09:13:35 +0200
From: Richard Leitner <richard.leitner@...ux.dev>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc: Dave Stevenson <dave.stevenson@...pberrypi.com>,
Mauro Carvalho Chehab <mchehab@...nel.org>, Lee Jones <lee@...nel.org>, Pavel Machek <pavel@...nel.org>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>, linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-leds@...r.kernel.org, Hans Verkuil <hverkuil@...nel.org>
Subject: Re: [PATCH v7 10/10] media: i2c: ov9282: dynamic flash_duration
maximum
Hi Sakari,
On Tue, Sep 02, 2025 at 12:16:51AM +0300, Sakari Ailus wrote:
> Hi Richard,
>
> On Mon, Sep 01, 2025 at 05:05:15PM +0200, Richard Leitner wrote:
> > This patch sets the current exposure time as maximum for the
> > flash_duration control. As Flash/Strobes which are longer than the
> > exposure time have no effect.
> >
> > Signed-off-by: Richard Leitner <richard.leitner@...ux.dev>
> > ---
> > drivers/media/i2c/ov9282.c | 30 ++++++++++++++++++++++++++----
> > 1 file changed, 26 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/media/i2c/ov9282.c b/drivers/media/i2c/ov9282.c
> > index b104ae77f00e9e7777342e48b7bf3caa6d297f69..3253d9f271cb3caef6d85837ebec4f5beb466a4d 100644
> > --- a/drivers/media/i2c/ov9282.c
> > +++ b/drivers/media/i2c/ov9282.c
> > @@ -198,6 +198,7 @@ struct ov9282_mode {
> > * @exp_ctrl: Pointer to exposure control
> > * @again_ctrl: Pointer to analog gain control
> > * @pixel_rate: Pointer to pixel rate control
> > + * @flash_duration: Pointer to flash duration control
> > * @vblank: Vertical blanking in lines
> > * @noncontinuous_clock: Selection of CSI2 noncontinuous clock mode
> > * @cur_mode: Pointer to current selected sensor mode
> > @@ -220,6 +221,7 @@ struct ov9282 {
> > struct v4l2_ctrl *again_ctrl;
> > };
> > struct v4l2_ctrl *pixel_rate;
> > + struct v4l2_ctrl *flash_duration;
> > u32 vblank;
> > bool noncontinuous_clock;
> > const struct ov9282_mode *cur_mode;
> > @@ -611,6 +613,15 @@ static int ov9282_update_controls(struct ov9282 *ov9282,
> > mode->vblank_max, 1, mode->vblank);
> > }
> >
> > +static u32 ov9282_exposure_to_us(struct ov9282 *ov9282, u32 exposure)
> > +{
> > + /* calculate exposure time in µs */
> > + u32 frame_width = ov9282->cur_mode->width + ov9282->hblank_ctrl->val;
> > + u32 trow_us = (frame_width * 1000000UL) / ov9282->pixel_rate->val;
>
> Redundant parentheses.
True. Will fix this. Thanks for the catch.
>
> > +
> > + return exposure * trow_us;
> > +}
> > +
> > /**
> > * ov9282_update_exp_gain() - Set updated exposure and gain
> > * @ov9282: pointer to ov9282 device
> > @@ -622,9 +633,10 @@ static int ov9282_update_controls(struct ov9282 *ov9282,
> > static int ov9282_update_exp_gain(struct ov9282 *ov9282, u32 exposure, u32 gain)
> > {
> > int ret;
> > + u32 exposure_us = ov9282_exposure_to_us(ov9282, exposure);
> >
> > - dev_dbg(ov9282->dev, "Set exp %u, analog gain %u",
> > - exposure, gain);
> > + dev_dbg(ov9282->dev, "Set exp %u (~%u us), analog gain %u",
> > + exposure, exposure_us, gain);
> >
> > ret = ov9282_write_reg(ov9282, OV9282_REG_HOLD, 1, 1);
> > if (ret)
> > @@ -635,6 +647,12 @@ static int ov9282_update_exp_gain(struct ov9282 *ov9282, u32 exposure, u32 gain)
> > goto error_release_group_hold;
> >
> > ret = ov9282_write_reg(ov9282, OV9282_REG_AGAIN, 1, gain);
> > + if (ret)
> > + goto error_release_group_hold;
> > +
> > + ret = __v4l2_ctrl_modify_range(ov9282->flash_duration,
> > + 0, exposure_us, 1,
> > + OV9282_FLASH_DURATION_DEFAULT);
> >
> > error_release_group_hold:
> > ov9282_write_reg(ov9282, OV9282_REG_HOLD, 1, 0);
> > @@ -1420,6 +1438,7 @@ static int ov9282_init_controls(struct ov9282 *ov9282)
> > struct v4l2_fwnode_device_properties props;
> > struct v4l2_ctrl *ctrl;
> > u32 hblank_min;
> > + u32 exposure_us;
> > u32 lpfr;
> > int ret;
> >
> > @@ -1491,8 +1510,11 @@ static int ov9282_init_controls(struct ov9282 *ov9282)
> > /* Flash/Strobe controls */
> > v4l2_ctrl_new_std(ctrl_hdlr, &ov9282_ctrl_ops, V4L2_CID_FLASH_HW_STROBE_SIGNAL, 0, 1, 1, 0);
> >
> > - v4l2_ctrl_new_std(ctrl_hdlr, &ov9282_ctrl_ops, V4L2_CID_FLASH_DURATION,
> > - 0, 13900, 1, 8);
> > + exposure_us = ov9282_exposure_to_us(ov9282, OV9282_EXPOSURE_DEFAULT);
> > + ov9282->flash_duration = v4l2_ctrl_new_std(ctrl_hdlr,
> > + &ov9282_ctrl_ops, V4L2_CID_FLASH_DURATION,
> > + 0, exposure_us,
> > + 1, OV9282_FLASH_DURATION_DEFAULT);
>
> Wrap this differently, please, e.g. after '='.
This is wrapped the same way as all other v4l2_ctrl_new_X() calls in
ov9282_init_controls(). Therefore I've chosen to do it this way here
too.
So if I'm going to change this one, IMHO all others should be changed
too (exp_ctrl, again_ctrl, vblank_ctrl, pixel_rate, link_freq_ctrl,
hblank_ctrl). Is this intended?
If so I'm wondering if this would be a suiteable approach?
ov9282->flash_duration =
v4l2_ctrl_new_std(ctrl_hdlr,
&ov9282_ctrl_ops, V4L2_CID_FLASH_DURATION,
0, exposure_us,
1, OV9282_FLASH_DURATION_DEFAULT);
It is fine for checkpatch, but introduces a newline for every ctrl and
tbh I'm not sure if it improves readability?
>
> >
> > ctrl = v4l2_ctrl_new_std_menu(ctrl_hdlr, &ov9282_ctrl_ops,
> > V4L2_CID_FLASH_STROBE_SOURCE,
> >
>
> To me the set looks good but I wouldn't mind about having a bit more
> review.
Thanks for your continuous feedback! It improved the series a lot!
Is there anyhthing I can assists/help?
>
> --
> Kind regards,
>
> Sakari Ailus
regards;rl
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