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From:   Mikhail Rudenko <mike.rudenko@gmail.com>
To:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc:     linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        Jacopo Mondi <jacopo@jmondi.org>,
        Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        Dave Stevenson <dave.stevenson@raspberrypi.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>
Subject: Re: [PATCH 11/19] media: i2c: ov4689: Implement vflip/hflip controls
Date:   Tue, 12 Dec 2023 15:42:13 +0300
In-reply-to: <20231211221059.GJ27535@pendragon.ideasonboard.com>
Message-ID: <87h6knpot0.fsf@gmail.com>
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On 2023-12-12 at 00:10 +02, Laurent Pinchart <laurent.pinchart@ideasonboard.com> wrote:

> Hi Mikhail,
>
> Thank you for the patch.
>
> On Mon, Dec 11, 2023 at 08:50:14PM +0300, Mikhail Rudenko wrote:
>> The OV4689 sensor supports horizontal and vertical flipping. Add
>> appropriate controls to the driver. Toggling both array flip and
>> digital flip bits allows to achieve flipping while maintaining output
>> Bayer order. Note that the default value of hflip control corresponds
>> to both bits set, as it was before this patch.
>
> What happens if only hlip or vflip is set, does the bayer pattern change
> ?

If one changes both digital and analog flip bits (and this is what this
driver does), bayer pattern stay the same for all possible vflip/hflip
combinations. Unfortunately, the datasheet does not say much about these
bits, but I have a hypothesis that the on-sensor ISP can somehow reorder
pixels to keep the same bayer battern when asked.


> Sakari, I think this patch could use your attention.
>
>> Signed-off-by: Mikhail Rudenko <mike.rudenko@gmail.com>
>> ---
>>  drivers/media/i2c/ov4689.c | 24 ++++++++++++++++++++++--
>>  1 file changed, 22 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/media/i2c/ov4689.c b/drivers/media/i2c/ov4689.c
>> index 67d4004bdcfb..62aeae43d749 100644
>> --- a/drivers/media/i2c/ov4689.c
>> +++ b/drivers/media/i2c/ov4689.c
>> @@ -46,6 +46,14 @@
>>  #define OV4689_HTS_DIVIDER		4
>>  #define OV4689_HTS_MAX			0x7fff
>>
>> +#define OV4689_REG_TIMING_FORMAT1	CCI_REG8(0x3820)
>> +#define OV4689_REG_TIMING_FORMAT2	CCI_REG8(0x3821)
>> +#define OV4689_TIMING_FLIP_MASK		GENMASK(2, 1)
>> +#define OV4689_TIMING_FLIP_ARRAY	BIT(1)
>> +#define OV4689_TIMING_FLIP_DIGITAL	BIT(2)
>> +#define OV4689_TIMING_FLIP_BOTH		(OV4689_TIMING_FLIP_ARRAY |\
>> +					 OV4689_TIMING_FLIP_DIGITAL)
>> +
>>  #define OV4689_LANES			4
>>  #define OV4689_XVCLK_FREQ		24000000
>>
>> @@ -183,7 +191,6 @@ static const struct cci_reg_sequence ov4689_2688x1520_regs[] = {
>>  	{CCI_REG8(0x3811), 0x08}, /* H_WIN_OFF_L h_win_off[7:0] = 0x08*/
>>  	{CCI_REG8(0x3813), 0x04}, /* V_WIN_OFF_L v_win_off[7:0] = 0x04 */
>>  	{CCI_REG8(0x3819), 0x01}, /* VSYNC_END_L vsync_end_point[7:0] = 0x01 */
>> -	{CCI_REG8(0x3821), 0x06}, /* TIMING_FORMAT2 array_h_mirror = 1, digital_h_mirror = 1 */
>>
>>  	/* OTP control */
>>  	{CCI_REG8(0x3d85), 0x36}, /* OTP_REG85 OTP_power_up_load_setting_enable = 1,
>> @@ -605,6 +612,16 @@ static int ov4689_set_ctrl(struct v4l2_ctrl *ctrl)
>>  			  (val + ov4689->cur_mode->width) /
>>  			  OV4689_HTS_DIVIDER, &ret);
>>  		break;
>> +	case V4L2_CID_VFLIP:
>> +		cci_update_bits(regmap, OV4689_REG_TIMING_FORMAT1,
>> +				OV4689_TIMING_FLIP_MASK,
>> +				val ? OV4689_TIMING_FLIP_BOTH : 0, &ret);
>> +		break;
>> +	case V4L2_CID_HFLIP:
>> +		cci_update_bits(regmap, OV4689_REG_TIMING_FORMAT2,
>> +				OV4689_TIMING_FLIP_MASK,
>> +				val ? 0 : OV4689_TIMING_FLIP_BOTH, &ret);
>> +		break;
>>  	default:
>>  		dev_warn(dev, "%s Unhandled id:0x%x, val:0x%x\n",
>>  			 __func__, ctrl->id, val);
>> @@ -633,7 +650,7 @@ static int ov4689_initialize_controls(struct ov4689 *ov4689)
>>
>>  	handler = &ov4689->ctrl_handler;
>>  	mode = ov4689->cur_mode;
>> -	ret = v4l2_ctrl_handler_init(handler, 11);
>> +	ret = v4l2_ctrl_handler_init(handler, 13);
>
> This should be 12 if my comment on 10/19 is correct. Further patches in
> the series may need to be adjusted too.

Ack, will fix in v2.

>>  	if (ret)
>>  		return ret;
>>
>> @@ -673,6 +690,9 @@ static int ov4689_initialize_controls(struct ov4689 *ov4689)
>>  				     ARRAY_SIZE(ov4689_test_pattern_menu) - 1,
>>  				     0, 0, ov4689_test_pattern_menu);
>>
>> +	v4l2_ctrl_new_std(handler, &ov4689_ctrl_ops, V4L2_CID_VFLIP, 0, 1, 1, 0);
>> +	v4l2_ctrl_new_std(handler, &ov4689_ctrl_ops, V4L2_CID_HFLIP, 0, 1, 1, 0);
>> +
>>  	if (handler->error) {
>>  		ret = handler->error;
>>  		dev_err(ov4689->dev, "Failed to init controls(%d)\n", ret);


--
Best regards,
Mikhail Rudenko