media: v4l: common: Add a function to obtain best size from a list

Add a function (as well as a helper macro) to obtain the best size in a
list of device specific sizes. This helps writing drivers as well as
aligns interface behaviour across drivers.

The struct in which this information is contained in is typically specific
to the driver, therefore the existing function v4l2_find_nearest_format()
does not address the need.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c
index 96c1b31de9e3..9b65529dfaf6 100644
--- a/drivers/media/v4l2-core/v4l2-common.c
+++ b/drivers/media/v4l2-core/v4l2-common.c
@@ -383,6 +383,36 @@ v4l2_find_nearest_format(const struct v4l2_frmsize_discrete *sizes,
 }
 EXPORT_SYMBOL_GPL(v4l2_find_nearest_format);
 
+const void *
+__v4l2_find_nearest_size(const void *array, size_t array_size,
+			 size_t entry_size, size_t width_offset,
+			 size_t height_offset, s32 width, s32 height)
+{
+	u32 error, min_error = U32_MAX;
+	const void *best = NULL;
+	unsigned int i;
+
+	if (!array)
+		return NULL;
+
+	for (i = 0; i < array_size; i++, array += entry_size) {
+		const u32 *entry_width = array + width_offset;
+		const u32 *entry_height = array + height_offset;
+
+		error = abs(*entry_width - width) + abs(*entry_height - height);
+		if (error > min_error)
+			continue;
+
+		min_error = error;
+		best = array;
+		if (!error)
+			break;
+	}
+
+	return best;
+}
+EXPORT_SYMBOL_GPL(__v4l2_find_nearest_size);
+
 void v4l2_get_timestamp(struct timeval *tv)
 {
 	struct timespec ts;