Re: [PATCH 4/7] media: atmel: atmel-isc: add support for DO_WHITE_BALANCE

[Hans Verkuil]

On 4/15/19 8:43 AM, Eugen.Hristev@xxxxxxxxxxxxx wrote:
> 
> 
> On 10.04.2019 17:26, Hans Verkuil wrote:
> 
>>
>> On 4/9/19 1:07 PM, Eugen.Hristev@xxxxxxxxxxxxx wrote:
>>> From: Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx>
>>>
>>> This adds support for the 'button' control DO_WHITE_BALANCE
>>> This feature will enable the ISC to compute the white balance coefficients
>>> in a one time shot, at the user discretion.
>>> This can be used if a color chart/grey chart is present in front of the camera.
>>> The ISC will adjust the coefficients and have them fixed until next balance
>>> or until sensor mode is changed.
>>> This is particularly useful for white balance adjustment in different
>>> lighting scenarios, and then taking photos to similar scenery.
>>> The old auto white balance stays in place, where the ISC will adjust every
>>> 4 frames to the current scenery lighting, if the scenery is approximately
>>> grey in average, otherwise grey world algorithm fails.
>>> One time white balance adjustments needs streaming to be enabled, such that
>>> capture is enabled and the histogram has data to work with.
>>> Histogram without capture does not work in this hardware module.
>>>
>>> To disable auto white balance feature (first step)
>>> v4l2-ctl --set-ctrl=white_balance_automatic=0
>>>
>>> To start the one time white balance procedure:
>>> v4l2-ctl --set-ctrl=do_white_balance=1
>>>
>>> User controls now include the do_white_balance ctrl:
>>> User Controls
>>>
>>>                       brightness 0x00980900 (int)    : min=-1024 max=1023 step=1 default=0 value=0 flags=slider
>>>                         contrast 0x00980901 (int)    : min=-2048 max=2047 step=1 default=256 value=256 flags=slider
>>>          white_balance_automatic 0x0098090c (bool)   : default=1 value=1
>>>                 do_white_balance 0x0098090d (button) : flags=write-only, execute-on-write
>>>                            gamma 0x00980910 (int)    : min=0 max=2 step=1 default=2 value=2 flags=slider
>>>
>>> Signed-off-by: Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx>
>>> ---
>>>   drivers/media/platform/atmel/atmel-isc.c | 74 +++++++++++++++++++++++++++++---
>>>   1 file changed, 69 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/media/platform/atmel/atmel-isc.c b/drivers/media/platform/atmel/atmel-isc.c
>>> index f6b8b00e..e516805 100644
>>> --- a/drivers/media/platform/atmel/atmel-isc.c
>>> +++ b/drivers/media/platform/atmel/atmel-isc.c
>>> @@ -167,6 +167,9 @@ struct isc_ctrls {
>>>   	u32 brightness;
>>>   	u32 contrast;
>>>   	u8 gamma_index;
>>> +#define ISC_WB_NONE	0
>>> +#define ISC_WB_AUTO	1
>>> +#define ISC_WB_ONETIME	2
>>>   	u8 awb;
>>>   
>>>   	/* one for each component : GR, R, GB, B */
>>> @@ -210,6 +213,7 @@ struct isc_device {
>>>   	struct fmt_config	try_config;
>>>   
>>>   	struct isc_ctrls	ctrls;
>>> +	struct v4l2_ctrl	*do_wb_ctrl;
>>>   	struct work_struct	awb_work;
>>>   
>>>   	struct mutex		lock;
>>> @@ -809,7 +813,7 @@ static void isc_set_pipeline(struct isc_device *isc, u32 pipeline)
>>>   
>>>   	bay_cfg = isc->config.sd_format->cfa_baycfg;
>>>   
>>> -	if (!ctrls->awb)
>>> +	if (ctrls->awb == ISC_WB_NONE)
>>>   		isc_reset_awb_ctrls(isc);
>>>   
>>>   	regmap_write(regmap, ISC_WB_CFG, bay_cfg);
>>> @@ -1928,7 +1932,7 @@ static void isc_awb_work(struct work_struct *w)
>>>   	baysel = isc->config.sd_format->cfa_baycfg << ISC_HIS_CFG_BAYSEL_SHIFT;
>>>   
>>>   	/* if no more auto white balance, reset controls. */
>>> -	if (!ctrls->awb)
>>> +	if (ctrls->awb == ISC_WB_NONE)
>>>   		isc_reset_awb_ctrls(isc);
>>>   
>>>   	pm_runtime_get_sync(isc->dev);
>>> @@ -1937,7 +1941,7 @@ static void isc_awb_work(struct work_struct *w)
>>>   	 * only update if we have all the required histograms and controls
>>>   	 * if awb has been disabled, we need to reset registers as well.
>>>   	 */
>>> -	if (hist_id == ISC_HIS_CFG_MODE_GR || !ctrls->awb) {
>>> +	if (hist_id == ISC_HIS_CFG_MODE_GR || ctrls->awb == ISC_WB_NONE) {
>>>   		/*
>>>   		 * It may happen that DMA Done IRQ will trigger while we are
>>>   		 * updating white balance registers here.
>>> @@ -1947,6 +1951,16 @@ static void isc_awb_work(struct work_struct *w)
>>>   		spin_lock_irqsave(&isc->awb_lock, flags);
>>>   		isc_update_awb_ctrls(isc);
>>>   		spin_unlock_irqrestore(&isc->awb_lock, flags);
>>> +
>>> +		/*
>>> +		 * if we are doing just the one time white balance adjustment,
>>> +		 * we are basically done.
>>> +		 */
>>> +		if (ctrls->awb == ISC_WB_ONETIME) {
>>> +			v4l2_info(&isc->v4l2_dev,
>>> +				  "Completed one time white-balance adjustment.\n");
>>> +			ctrls->awb = ISC_WB_NONE;
>>> +		}
>>>   	}
>>>   	regmap_write(regmap, ISC_HIS_CFG, hist_id | baysel | ISC_HIS_CFG_RAR);
>>>   	isc_update_profile(isc);
>>> @@ -1974,10 +1988,56 @@ static int isc_s_ctrl(struct v4l2_ctrl *ctrl)
>>>   		ctrls->gamma_index = ctrl->val;
>>>   		break;
>>>   	case V4L2_CID_AUTO_WHITE_BALANCE:
>>> -		ctrls->awb = ctrl->val;
>>> +		if (ctrl->val == 1) {
>>> +			ctrls->awb = ISC_WB_AUTO;
>>> +			v4l2_ctrl_activate(isc->do_wb_ctrl, false);
>>> +		} else {
>>> +			ctrls->awb = ISC_WB_NONE;
>>> +			v4l2_ctrl_activate(isc->do_wb_ctrl, true);
>>> +		}
>>> +		/* we did not configure ISC yet */
>>> +		if (!isc->config.sd_format)
>>> +			break;
>>> +
>>> +		if (!ISC_IS_FORMAT_RAW(isc->config.sd_format->mbus_code)) {
>>> +			v4l2_err(&isc->v4l2_dev,
>>> +				 "White balance adjustments available only if sensor is in RAW mode.\n");
>>
>> This isn't an error, instead if the format isn't raw, then deactivate
>> the control (see v4l2_ctrl_activate()). That way the control framework
>> will handle this.
>>
>>> +			return 0;
>>> +		}
>>> +
>>>   		if (ctrls->hist_stat != HIST_ENABLED) {
>>>   			isc_reset_awb_ctrls(isc);
>>>   		}
>>> +
>>> +		if (isc->ctrls.awb && vb2_is_streaming(&isc->vb2_vidq) &&
>>> +		    ISC_IS_FORMAT_RAW(isc->config.sd_format->mbus_code))
>>> +			isc_set_histogram(isc, true);
>>> +
>>> +		break;
>>> +	case V4L2_CID_DO_WHITE_BALANCE:
>>> +		/* we did not configure ISC yet */
>>> +		if (!isc->config.sd_format)
>>> +			break;
>>> +
>>> +		if (ctrls->awb == ISC_WB_AUTO) {
>>> +			v4l2_err(&isc->v4l2_dev,
>>> +				 "To use one time white-balance adjustment, disable auto white balance first.\n");
>>
>> I'd do this differently: if auto whitebalance is already on, then just do
>> nothing for V4L2_CID_DO_WHITE_BALANCE.
>>
>>> +			return -EAGAIN;
>>> +		}
>>> +		if (!vb2_is_streaming(&isc->vb2_vidq)) {
>>> +			v4l2_err(&isc->v4l2_dev,
>>> +				 "One time white-balance adjustment requires streaming to be enabled.\n");
>>
>> This too should use v4l2_ctrl_activate(): activate the control in start_streaming,
>> deactivate in stop_streaming (and when the control is created).
>>
>>> +			return -EAGAIN;
>>> +		}
>>> +
>>> +		if (!ISC_IS_FORMAT_RAW(isc->config.sd_format->mbus_code)) {
>>> +			v4l2_err(&isc->v4l2_dev,
>>> +				 "White balance adjustments available only if sensor is in RAW mode.\n");
>>
>> Same note as above: use v4l2_ctrl_activate() for this.
> 
> Hello Hans,
> 
> I used v4l2_ctrl_activate with false parameter, and the v4l2-ctl -l 
> looks like this:
> 
> 
>             do_white_balance (button) : flags=inactive, write-only, 
> execute-on-write
> 
> But the inactive flag looks to be only for display purposes, as issuing :
> 
> v4l2-ctl --set-ctrl=do_white_balance=1
> 
> will continue to call my ctrl callback as if the control is still active.
> 
> Am I missing something here ? v4l2_s_ctrl does not check for INACTIVE 
> status.

No, you are correct. I got confused with FLAG_GRABBED.

In any case, the idea was right, but you do have to add code to s_ctrl
to handle this (e.g. if the INACTIVE flag is set, then just do nothing).

The INACTIVE flag is meant to communicate that the control can still be
set, but it just doesn't do anything. qv4l2 will disable the control if
this flag is set.

Note that when you set an inactive control, the control value should
still be updated even if it isn't used at the moment. If the configuration
changes so that the control becomes active again, then that last set
value should be used by the hardware.

This is the reason why s_ctrl is still called.

Regards,

	Hans

> 
> Thanks
> 
>>
>>> +			return -EAGAIN;
>>> +		}
>>> +		ctrls->awb = ISC_WB_ONETIME;
>>> +		isc_set_histogram(isc, true);
>>> +		v4l2_info(&isc->v4l2_dev, "One time white-balance started.\n");
>>
>> Make this v4l2_dbg.
>>
>>>   		break;
>>>   	default:
>>>   		return -EINVAL;
>>> @@ -2000,7 +2060,7 @@ static int isc_ctrl_init(struct isc_device *isc)
>>>   	ctrls->hist_stat = HIST_INIT;
>>>   	isc_reset_awb_ctrls(isc);
>>>   
>>> -	ret = v4l2_ctrl_handler_init(hdl, 4);
>>> +	ret = v4l2_ctrl_handler_init(hdl, 5);
>>>   	if (ret < 0)
>>>   		return ret;
>>>   
>>> @@ -2012,6 +2072,10 @@ static int isc_ctrl_init(struct isc_device *isc)
>>>   	v4l2_ctrl_new_std(hdl, ops, V4L2_CID_GAMMA, 0, GAMMA_MAX, 1, 2);
>>>   	v4l2_ctrl_new_std(hdl, ops, V4L2_CID_AUTO_WHITE_BALANCE, 0, 1, 1, 1);
>>>   
>>> +	/* do_white_balance is a button, so min,max,step,default are ignored */
>>> +	isc->do_wb_ctrl = v4l2_ctrl_new_std(hdl, ops, V4L2_CID_DO_WHITE_BALANCE,
>>> +					    0, 0, 0, 0);
>>> +
>>>   	v4l2_ctrl_handler_setup(hdl);
>>>   
>>>   	return 0;
>>>
>>
>> Regards,
>>
>> 	Hans
>>