[PATCH v3 2/4] media: v4l2-common: Add v4l2_fill_pixfmt_aligned() helper

[Tommaso Merciai]

Add v4l2_fill_pixfmt_aligned(), a variant of v4l2_fill_pixfmt()
that accepts a stride_alignment parameter, mirroring the existing
v4l2_fill_pixfmt_mp() / v4l2_fill_pixfmt_mp_aligned() pair.

v4l2_fill_pixfmt() is refactored to call v4l2_fill_pixfmt_aligned()
with stride_alignment=1, preserving its existing behaviour.

The new helper is needed by drivers whose DMA engine requires the
line stride to be a multiple of a specific value, such as the
Renesas RZ/G3E CRU which requires 128-byte alignment.

Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@xxxxxxxxxxxxxx>
---
v2->v3:
 - No changes, just moved to from PATCH 3/4 to PATCH 2/4

v1->v2:
 - Move v4l2_fill_pixfmt() into v4l2-common.h as inline wrapper
 - Add v4l2_fill_pixfmt_aligned() helper documentation.

 drivers/media/v4l2-core/v4l2-common.c | 12 +++++----
 include/media/v4l2-common.h           | 38 +++++++++++++++++++++++++--
 2 files changed, 43 insertions(+), 7 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c
index 54995ba8c20d..2ce4f1c20fbc 100644
--- a/drivers/media/v4l2-core/v4l2-common.c
+++ b/drivers/media/v4l2-core/v4l2-common.c
@@ -537,8 +537,8 @@ int v4l2_fill_pixfmt_mp_aligned(struct v4l2_pix_format_mplane *pixfmt,
 }
 EXPORT_SYMBOL_GPL(v4l2_fill_pixfmt_mp_aligned);
 
-int v4l2_fill_pixfmt(struct v4l2_pix_format *pixfmt, u32 pixelformat,
-		     u32 width, u32 height)
+int v4l2_fill_pixfmt_aligned(struct v4l2_pix_format *pixfmt, u32 pixelformat,
+			     u32 width, u32 height, u8 stride_alignment)
 {
 	const struct v4l2_format_info *info;
 	int i;
@@ -554,15 +554,17 @@ int v4l2_fill_pixfmt(struct v4l2_pix_format *pixfmt, u32 pixelformat,
 	pixfmt->width = width;
 	pixfmt->height = height;
 	pixfmt->pixelformat = pixelformat;
-	pixfmt->bytesperline = v4l2_format_plane_stride(info, 0, width, 1);
+	pixfmt->bytesperline = v4l2_format_plane_stride(info, 0, width,
+							stride_alignment);
 	pixfmt->sizeimage = 0;
 
 	for (i = 0; i < info->comp_planes; i++)
 		pixfmt->sizeimage +=
-			v4l2_format_plane_size(info, i, width, height, 1);
+			v4l2_format_plane_size(info, i, width, height,
+					       stride_alignment);
 	return 0;
 }
-EXPORT_SYMBOL_GPL(v4l2_fill_pixfmt);
+EXPORT_SYMBOL_GPL(v4l2_fill_pixfmt_aligned);
 
 #ifdef CONFIG_MEDIA_CONTROLLER
 static s64 v4l2_get_link_freq_ctrl(struct v4l2_ctrl_handler *handler,
diff --git a/include/media/v4l2-common.h b/include/media/v4l2-common.h
index 749fe38c134e..be4dd9762196 100644
--- a/include/media/v4l2-common.h
+++ b/include/media/v4l2-common.h
@@ -554,8 +554,42 @@ static inline bool v4l2_is_format_bayer(const struct v4l2_format_info *f)
 const struct v4l2_format_info *v4l2_format_info(u32 format);
 void v4l2_apply_frmsize_constraints(u32 *width, u32 *height,
 				    const struct v4l2_frmsize_stepwise *frmsize);
-int v4l2_fill_pixfmt(struct v4l2_pix_format *pixfmt, u32 pixelformat,
-		     u32 width, u32 height);
+
+/**
+ * v4l2_fill_pixfmt_aligned - Fill in a &struct v4l2_pix_format with stride
+ *	alignment requirements.
+ *
+ * @pixfmt: pointer to the &struct v4l2_pix_format to be filled
+ * @pixelformat: the V4L2 pixel format (V4L2_PIX_FMT_*)
+ * @width: image width in pixels
+ * @height: image height in pixels
+ * @stride_alignment: stride alignment in bytes, must be a power of 2
+ *
+ * Fills all fields of @pixfmt for the given pixel format, dimensions, and
+ * stride alignment. Only formats stored in a single memory plane are
+ * supported; returns -EINVAL for multi-memory-plane formats.
+ *
+ * @pixfmt->bytesperline is set to the stride of the primary (plane 0) plane,
+ * rounded up to a multiple of @stride_alignment. For formats that store
+ * multiple component planes in a single memory buffer (e.g. NV12), the
+ * alignment applied to each component plane's stride is scaled relative to
+ * @stride_alignment so that the chroma stride remains consistently derivable
+ * from the luma stride. @pixfmt->bytesperline therefore reflects only the
+ * primary plane stride.
+ *
+ * @pixfmt->sizeimage is set to the total size in bytes of all component planes.
+ *
+ * Return: 0 on success, -EINVAL if @pixelformat is unknown or uses multiple
+ *	memory planes.
+ */
+int v4l2_fill_pixfmt_aligned(struct v4l2_pix_format *pixfmt, u32 pixelformat,
+			     u32 width, u32 height, u8 stride_alignment);
+
+static inline int v4l2_fill_pixfmt(struct v4l2_pix_format *pixfmt,
+				   u32 pixelformat, u32 width, u32 height)
+{
+	return v4l2_fill_pixfmt_aligned(pixfmt, pixelformat, width, height, 1);
+}
 
 /* @stride_alignment is a power of 2 value in bytes */
 int v4l2_fill_pixfmt_mp_aligned(struct v4l2_pix_format_mplane *pixfmt,
-- 
2.54.0