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Date:   Wed, 21 Sep 2022 04:06:04 +0300
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Ricardo Ribalda <ribalda@chromium.org>
Cc:     Mauro Carvalho Chehab <mchehab@kernel.org>,
        linux-kernel@vger.kernel.org, linux-media@vger.kernel.org
Subject: Re: [PATCH v2 1/2] media: uvcvideo: Implement mask for
 V4L2_CTRL_TYPE_MENU
Message-ID: <YypjfCLkmHRrsD66@pendragon.ideasonboard.com>
References: <20220920-standard-menues-v2-0-a35af3243c2f@chromium.org>
 <20220920-standard-menues-v2-1-a35af3243c2f@chromium.org>
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In-Reply-To: <20220920-standard-menues-v2-1-a35af3243c2f@chromium.org>
Precedence: bulk

Hi Ricardo,

Thank you for the patch.

On Wed, Sep 21, 2022 at 12:57:29AM +0200, Ricardo Ribalda wrote:
> Replace the count with a mask field that let us choose not only the max

s/let/lets/

> value, but also the minimum value and what values are valid in between.
> 
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> index 8c208db9600b..13bc57e2a08d 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c

Let's include <linux/bitops.h> in this file for ffs() and fls().

> @@ -524,7 +524,8 @@ static const struct uvc_control_mapping uvc_ctrl_mappings[] = {
>  		.v4l2_type	= V4L2_CTRL_TYPE_MENU,
>  		.data_type	= UVC_CTRL_DATA_TYPE_BITMASK,
>  		.menu_info	= exposure_auto_controls,
> -		.menu_count	= ARRAY_SIZE(exposure_auto_controls),
> +		.menu_mask	=
> +			BIT_MASK(ARRAY_SIZE(exposure_auto_controls)),

This fits on a single line.

>  		.slave_ids	= { V4L2_CID_EXPOSURE_ABSOLUTE, },
>  	},
>  	{
> @@ -730,7 +731,8 @@ static const struct uvc_control_mapping uvc_ctrl_mappings_uvc11[] = {
>  		.v4l2_type	= V4L2_CTRL_TYPE_MENU,
>  		.data_type	= UVC_CTRL_DATA_TYPE_ENUM,
>  		.menu_info	= power_line_frequency_controls,
> -		.menu_count	= ARRAY_SIZE(power_line_frequency_controls) - 1,
> +		.menu_mask	=
> +			BIT_MASK(ARRAY_SIZE(power_line_frequency_controls) - 1),

And this and the next hunk would benefit, I think, from exceeding the 80
columns.

>  	},
>  };
>  
> @@ -744,7 +746,8 @@ static const struct uvc_control_mapping uvc_ctrl_mappings_uvc15[] = {
>  		.v4l2_type	= V4L2_CTRL_TYPE_MENU,
>  		.data_type	= UVC_CTRL_DATA_TYPE_ENUM,
>  		.menu_info	= power_line_frequency_controls,
> -		.menu_count	= ARRAY_SIZE(power_line_frequency_controls),
> +		.menu_mask	=
> +			BIT_MASK(ARRAY_SIZE(power_line_frequency_controls)),
>  	},
>  };
>  
> @@ -974,7 +977,9 @@ static s32 __uvc_ctrl_get_value(struct uvc_control_mapping *mapping,
>  		const struct uvc_menu_info *menu = mapping->menu_info;
>  		unsigned int i;
>  
> -		for (i = 0; i < mapping->menu_count; ++i, ++menu) {
> +		for (i = 1; BIT(i) <= mapping->menu_mask; ++i, ++menu) {
> +			if (!test_bit(i, &mapping->menu_mask))

I may be missing something, but if i starts at 1, aren't you testing bit
N+1 for menu entry N ?

> +				continue;
>  			if (menu->value == value) {
>  				value = i;
>  				break;
> @@ -1148,12 +1153,14 @@ static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
>  
>  	switch (mapping->v4l2_type) {
>  	case V4L2_CTRL_TYPE_MENU:
> -		v4l2_ctrl->minimum = 0;
> -		v4l2_ctrl->maximum = mapping->menu_count - 1;
> +		v4l2_ctrl->minimum = ffs(mapping->menu_mask) - 1;
> +		v4l2_ctrl->maximum = fls(mapping->menu_mask) - 1;
>  		v4l2_ctrl->step = 1;
>  
>  		menu = mapping->menu_info;
> -		for (i = 0; i < mapping->menu_count; ++i, ++menu) {
> +		for (i = 1; BIT(i) <= mapping->menu_mask; ++i, ++menu) {
> +			if (!test_bit(i, &mapping->menu_mask))

Same here.

> +				continue;
>  			if (menu->value == v4l2_ctrl->default_value) {
>  				v4l2_ctrl->default_value = i;
>  				break;
> @@ -1268,7 +1275,7 @@ int uvc_query_v4l2_menu(struct uvc_video_chain *chain,
>  		goto done;
>  	}
>  
> -	if (query_menu->index >= mapping->menu_count) {
> +	if (!test_bit(query_menu->index, &mapping->menu_mask)) {
>  		ret = -EINVAL;
>  		goto done;
>  	}
> @@ -1776,8 +1783,13 @@ int uvc_ctrl_set(struct uvc_fh *handle,
>  		break;
>  
>  	case V4L2_CTRL_TYPE_MENU:
> -		if (xctrl->value < 0 || xctrl->value >= mapping->menu_count)
> +		if (xctrl->value < (ffs(mapping->menu_mask) - 1) ||
> +		    xctrl->value > (fls(mapping->menu_mask) - 1))
>  			return -ERANGE;
> +
> +		if (!test_bit(xctrl->value, &mapping->menu_mask))
> +			return -EINVAL;
> +
>  		value = mapping->menu_info[xctrl->value].value;
>  
>  		/*
> @@ -2227,7 +2239,7 @@ static int __uvc_ctrl_add_mapping(struct uvc_video_chain *chain,
>  
>  	INIT_LIST_HEAD(&map->ev_subs);
>  
> -	size = sizeof(*mapping->menu_info) * mapping->menu_count;
> +	size = sizeof(*mapping->menu_info) * fls(mapping->menu_mask);
>  	map->menu_info = kmemdup(mapping->menu_info, size, GFP_KERNEL);
>  	if (map->menu_info == NULL) {
>  		kfree(map->name);
> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> index 9c05776f11d1..09cc459c1253 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -2675,7 +2675,8 @@ static const struct uvc_control_mapping uvc_ctrl_power_line_mapping_limited = {
>  	.v4l2_type	= V4L2_CTRL_TYPE_MENU,
>  	.data_type	= UVC_CTRL_DATA_TYPE_ENUM,
>  	.menu_info	= power_line_frequency_controls_limited,
> -	.menu_count	= ARRAY_SIZE(power_line_frequency_controls_limited),
> +	.menu_mask	=
> +		BIT_MASK(ARRAY_SIZE(power_line_frequency_controls_limited)),

Here too I'd avoid the line wrap.

>  };
>  
>  static const struct uvc_device_info uvc_ctrl_power_line_limited = {
> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> index 4cc3fa6b8c98..07c7acce8025 100644
> --- a/drivers/media/usb/uvc/uvc_v4l2.c
> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> @@ -80,7 +80,7 @@ static int uvc_ioctl_ctrl_map(struct uvc_video_chain *chain,
>  			goto free_map;
>  		}
>  
> -		map->menu_count = xmap->menu_count;
> +		map->menu_mask = BIT_MASK(xmap->menu_count);
>  		break;
>  
>  	default:
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index 24c911aeebce..fde4e975334f 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -255,7 +255,7 @@ struct uvc_control_mapping {
>  	u32 data_type;
>  
>  	const struct uvc_menu_info *menu_info;
> -	u32 menu_count;
> +	unsigned long menu_mask;
>  
>  	u32 master_id;
>  	s32 master_manual;

-- 
Regards,

Laurent Pinchart