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Subject: Re: [PATCH v3 2/2] media: vimc: Add a control to display info on test
 image
To:     Kaaira Gupta <kgupta@es.iitr.ac.in>
Cc:     Helen Koike <helen.koike@collabora.com>,
        Shuah Khan <skhan@linuxfoundation.org>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        Kieran Bingham <kieran.bingham@ideasonboard.com>,
        hverkuil@xs4all.nl
References: <20200618190506.11892-1-kgupta@es.iitr.ac.in>
 <20200618190506.11892-3-kgupta@es.iitr.ac.in>
 <d62583ab-7dd3-9a37-c94d-99fae0f29357@collabora.com>
 <20200621203256.GA13040@kaaira-HP-Pavilion-Notebook>
From:   Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Message-ID: <a8fb5c4c-4994-f53d-838d-0c10d796b997@collabora.com>
Date:   Mon, 22 Jun 2020 16:36:54 +0200
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On 21.06.20 22:32, Kaaira Gupta wrote:
> On Sat, Jun 20, 2020 at 12:05:28PM +0200, Dafna Hirschfeld wrote:
>> Hi, thanks for the patch
>>
>> On 18.06.20 21:05, Kaaira Gupta wrote:
>>> Add a control in VIMC to display information such as the correct oder of
>>> colors for a given test pattern, brightness, hue, saturation, contrast
>>> and, width and height at sensor over test image; and display that
>>> information.
>>>
>>> Signed-off-by: Kaaira Gupta <kgupta@es.iitr.ac.in>
>>> ---
>>>    drivers/media/test-drivers/vimc/Kconfig       |  2 +
>>>    drivers/media/test-drivers/vimc/vimc-common.h |  1 +
>>>    drivers/media/test-drivers/vimc/vimc-sensor.c | 47 ++++++++++++++++++-
>>>    3 files changed, 49 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/media/test-drivers/vimc/Kconfig b/drivers/media/test-drivers/vimc/Kconfig
>>> index 4068a67585f9..da4b2ad6e40c 100644
>>> --- a/drivers/media/test-drivers/vimc/Kconfig
>>> +++ b/drivers/media/test-drivers/vimc/Kconfig
>>> @@ -2,6 +2,8 @@
>>>    config VIDEO_VIMC
>>>    	tristate "Virtual Media Controller Driver (VIMC)"
>>>    	depends on VIDEO_DEV && VIDEO_V4L2
>>> +	select FONT_SUPPORT
>>> +	select FONT_8x16
>>>    	select MEDIA_CONTROLLER
>>>    	select VIDEO_V4L2_SUBDEV_API
>>>    	select VIDEOBUF2_VMALLOC
>>> diff --git a/drivers/media/test-drivers/vimc/vimc-common.h b/drivers/media/test-drivers/vimc/vimc-common.h
>>> index ae163dec2459..afda52253402 100644
>>> --- a/drivers/media/test-drivers/vimc/vimc-common.h
>>> +++ b/drivers/media/test-drivers/vimc/vimc-common.h
>>> @@ -20,6 +20,7 @@
>>>    #define VIMC_CID_VIMC_CLASS		(0x00f00000 | 1)
>>>    #define VIMC_CID_TEST_PATTERN		(VIMC_CID_VIMC_BASE + 0)
>>>    #define VIMC_CID_MEAN_WIN_SIZE		(VIMC_CID_VIMC_BASE + 1)
>>> +#define VIMC_CID_SHOW_INFO		(VIMC_CID_VIMC_BASE + 2)
>>>    #define VIMC_FRAME_MAX_WIDTH 4096
>>>    #define VIMC_FRAME_MAX_HEIGHT 2160
>>> diff --git a/drivers/media/test-drivers/vimc/vimc-sensor.c b/drivers/media/test-drivers/vimc/vimc-sensor.c
>>> index a2f09ac9a360..f5352b115aac 100644
>>> --- a/drivers/media/test-drivers/vimc/vimc-sensor.c
>>> +++ b/drivers/media/test-drivers/vimc/vimc-sensor.c
>>> @@ -5,6 +5,7 @@
>>>     * Copyright (C) 2015-2017 Helen Koike <helen.fornazier@gmail.com>
>>>     */
>>> +#include <linux/font.h>
>>>    #include <linux/v4l2-mediabus.h>
>>>    #include <linux/vmalloc.h>
>>>    #include <media/v4l2-ctrls.h>
>>> @@ -19,6 +20,7 @@ struct vimc_sen_device {
>>>    	struct v4l2_subdev sd;
>>>    	struct tpg_data tpg;
>>>    	u8 *frame;
>>> +	bool show_info;
>>
>> I see that vivid saves the 'v4l2_ctrl*' of the controls,
>> maybe you should also do that instead of saving a boolean,
> 
> Hi, I don't understand..isn't boolean the control?

You can see that vivid saves the controls as 'v4l2_ctrl*' and
then the value of the control can be read from the 'cur.val' field.
Note also that the mutex lock: "mutex_lock(dev->ctrl_hdl_user_vid.lock);"
when reading the values. This way you have don't have to set the value
yourself, the framework takes care of it. You only have to read the value.

> 
>>
>>>    	/* The active format */
>>>    	struct v4l2_mbus_framefmt mbus_format;
>>>    	struct v4l2_ctrl_handler hdl;
>>> @@ -185,10 +187,29 @@ static const struct v4l2_subdev_pad_ops vimc_sen_pad_ops = {
>>>    static void *vimc_sen_process_frame(struct vimc_ent_device *ved,
>>>    				    const void *sink_frame)
>>>    {
>>> +	u8 *basep[TPG_MAX_PLANES][2];
>>> +	char *order;
>>> +	char str[100];
>>> +	int line = 1;
>>
>> Those vars declarations can be inside the 'if (vsen->show_info)'
> 
> I declared it outside because I felt all declarations should be
> together?

Not crucial, but I think it is nicer to declare variables in the most inner scope where
they are used.

> 
>>
>>>    	struct vimc_sen_device *vsen = container_of(ved, struct vimc_sen_device,
>>>    						    ved);
>>> -
>>>    	tpg_fill_plane_buffer(&vsen->tpg, 0, 0, vsen->frame);
>>> +	if (vsen->show_info) {
>>> +		tpg_calc_text_basep(&vsen->tpg, basep, 0, vsen->frame);
>>> +		order = tpg_g_color_order(&vsen->tpg);
>>> +		tpg_gen_text(&vsen->tpg, basep, line++ * 16, 16, order);
>>> +		snprintf(str, sizeof(str), " brightness %3d, contrast %3d, saturation %3d, hue %d ",
>>> +			 vsen->tpg.brightness,
>>> +			 vsen->tpg.contrast,
>>> +			 vsen->tpg.saturation,
>>> +			 vsen->tpg.hue);
>>> +		tpg_gen_text(&vsen->tpg, basep, line++ * 16, 16, str);
>>> +
>>> +		snprintf(str, sizeof(str), " sensor size: %dx%d",
>>> +			 vsen->mbus_format.width, vsen->mbus_format.height);
>>> +		tpg_gen_text(&vsen->tpg, basep, line++ * 16, 16, str);
>>> +	}
>>> +
>>>    	return vsen->frame;
>>>    }
>>> @@ -200,6 +221,14 @@ static int vimc_sen_s_stream(struct v4l2_subdev *sd, int enable)
>>>    	if (enable) {
>>>    		const struct vimc_pix_map *vpix;
>>>    		unsigned int frame_size;
>>> +		const struct font_desc *font = find_font("VGA8x16");
>>> +
>>> +		if (font == NULL) {
>> Using 'if (!font)' is the way to check null pointer, instead of compering to null. Running checkpatch.pl with '--strict'
>> will catch that.
> 
> I didn't do that to be consistent with vivid's style of code. Plus I
> thought it makes it more clear to read. Should i change this?

I don't know why vivid do it this way.
Again, it is not that crucial, but in general it is better to send a patch that passes the issues
found in checkpatch.

Thanks,
Dafna

> 
>>> +			pr_err("vimc: could not find font\n");
>> 'dev_err' should be used instead of 'pr_err'.
> 
> yes sorry, i didn't now the difference.
> 
>>
>> Also, maybe checking the font here is a bit late, since the user already
>> wants to stream and expect the info to be shown.
>> Maybe it is better to check the font on 'vimc_sen_s_ctrl'.
> 
> Like show the control only of font is available?
> 
> I think showing the error is enough maybe?
> 
>>
>> Thanks,
>> Dafna
>>
>>> +			vsen->show_info = 0;
>>> +		} else {
>>> +			tpg_set_font(font->data);
>>> +		}
>>>    		/* Calculate the frame size */
>>>    		vpix = vimc_pix_map_by_code(vsen->mbus_format.code);
>>> @@ -269,6 +298,9 @@ static int vimc_sen_s_ctrl(struct v4l2_ctrl *ctrl)
>>>    	case V4L2_CID_SATURATION:
>>>    		tpg_s_saturation(&vsen->tpg, ctrl->val);
>>>    		break;
>>> +	case VIMC_CID_SHOW_INFO:
>>> +		vsen->show_info = ctrl->val;
>>> +		break;
>>>    	default:
>>>    		return -EINVAL;
>>>    	}
>>> @@ -307,6 +339,17 @@ static const struct v4l2_ctrl_config vimc_sen_ctrl_test_pattern = {
>>>    	.qmenu = tpg_pattern_strings,
>>>    };
>>> +static const struct v4l2_ctrl_config vimc_sen_ctrl_show_info = {
>>> +	.ops = &vimc_sen_ctrl_ops,
>>> +	.id = VIMC_CID_SHOW_INFO,
>>> +	.name = "Show Information",
>>> +	.type = V4L2_CTRL_TYPE_BOOLEAN,
>>> +	.min = 0,
>>> +	.max = 1,
>>> +	.step = 1,
>>> +	.def = 1,
>>> +};
>>> +
>>>    static struct vimc_ent_device *vimc_sen_add(struct vimc_device *vimc,
>>>    					    const char *vcfg_name)
>>>    {
>>> @@ -323,6 +366,7 @@ static struct vimc_ent_device *vimc_sen_add(struct vimc_device *vimc,
>>>    	v4l2_ctrl_new_custom(&vsen->hdl, &vimc_sen_ctrl_class, NULL);
>>>    	v4l2_ctrl_new_custom(&vsen->hdl, &vimc_sen_ctrl_test_pattern, NULL);
>>> +	v4l2_ctrl_new_custom(&vsen->hdl, &vimc_sen_ctrl_show_info, NULL);
>>>    	v4l2_ctrl_new_std(&vsen->hdl, &vimc_sen_ctrl_ops,
>>>    			  V4L2_CID_VFLIP, 0, 1, 1, 0);
>>>    	v4l2_ctrl_new_std(&vsen->hdl, &vimc_sen_ctrl_ops,
>>> @@ -362,6 +406,7 @@ static struct vimc_ent_device *vimc_sen_add(struct vimc_device *vimc,
>>>    	/* Initialize the frame format */
>>>    	vsen->mbus_format = fmt_default;
>>> +	vsen->show_info = vimc_sen_ctrl_show_info.def;
>>>    	return &vsen->ved;
>>>