[PATCH 0/2] media: imx-jpeg: Constify a few static structs

[PATCH 0/2] media: imx-jpeg: Constify a few static structs

[Rikard Falkeborn]

Constify two structs that are never modified.

The first patch constifies a static v4l2_m2m_ops struct which contains
function pointers.

The second constifies mxc_jpeg_fmt, which contains read-only data. In
order to do that, a number of function arguments, return values and
pointers was made const as well.

Rikard Falkeborn (2):
  media: imx-jpeg: Constify static struct v4l2_m2m_ops
  media: imx-jpeg: Constify static struct mxc_jpeg_fmt

 drivers/media/platform/imx-jpeg/mxc-jpeg.c | 18 +++++++++---------
 drivers/media/platform/imx-jpeg/mxc-jpeg.h | 18 +++++++++---------
 2 files changed, 18 insertions(+), 18 deletions(-)

-- 
2.32.0

[PATCH 1/2] media: imx-jpeg: Constify static struct v4l2_m2m_ops

[Rikard Falkeborn]

The only usage of mxc_jpeg_m2m_ops is to pass its address to
v4l2_m2m_init() which takes a pointer to const struct v4l2_m2m_ops. Make
it const to allow the compiler to put it in read-only memory.

Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
---
 drivers/media/platform/imx-jpeg/mxc-jpeg.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/platform/imx-jpeg/mxc-jpeg.c b/drivers/media/platform/imx-jpeg/mxc-jpeg.c
index 03b9264af068..3a49007e1264 100644
--- a/drivers/media/platform/imx-jpeg/mxc-jpeg.c
+++ b/drivers/media/platform/imx-jpeg/mxc-jpeg.c
@@ -1890,7 +1890,7 @@ static const struct v4l2_file_operations mxc_jpeg_fops = {
 	.mmap		= v4l2_m2m_fop_mmap,
 };
 
-static struct v4l2_m2m_ops mxc_jpeg_m2m_ops = {
+static const struct v4l2_m2m_ops mxc_jpeg_m2m_ops = {
 	.device_run	= mxc_jpeg_device_run,
 };
 
-- 
2.32.0

[PATCH 2/2] media: imx-jpeg: Constify static struct mxc_jpeg_fmt

[Rikard Falkeborn]

It is only read-from, so make it const. In order to be able to do this,
constify all places where mxc_jpeg_fmt is used, in function arguments,
return values and pointers. On top of that, make the name a pointer to
const char.

On aarch64, this shrinks object code size with 550 bytes with gcc 11.1.0,
and almost 2kB with clang 12.0.0.

Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
---
 drivers/media/platform/imx-jpeg/mxc-jpeg.c | 16 ++++++++--------
 drivers/media/platform/imx-jpeg/mxc-jpeg.h | 18 +++++++++---------
 2 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/drivers/media/platform/imx-jpeg/mxc-jpeg.c b/drivers/media/platform/imx-jpeg/mxc-jpeg.c
index 3a49007e1264..755138063ee6 100644
--- a/drivers/media/platform/imx-jpeg/mxc-jpeg.c
+++ b/drivers/media/platform/imx-jpeg/mxc-jpeg.c
@@ -62,7 +62,7 @@
 #include "mxc-jpeg-hw.h"
 #include "mxc-jpeg.h"
 
-static struct mxc_jpeg_fmt mxc_formats[] = {
+static const struct mxc_jpeg_fmt mxc_formats[] = {
 	{
 		.name		= "JPEG",
 		.fourcc		= V4L2_PIX_FMT_JPEG,
@@ -341,7 +341,7 @@ static inline struct mxc_jpeg_ctx *mxc_jpeg_fh_to_ctx(struct v4l2_fh *fh)
 	return container_of(fh, struct mxc_jpeg_ctx, fh);
 }
 
-static int enum_fmt(struct mxc_jpeg_fmt *mxc_formats, int n,
+static int enum_fmt(const struct mxc_jpeg_fmt *mxc_formats, int n,
 		    struct v4l2_fmtdesc *f, u32 type)
 {
 	int i, num = 0;
@@ -368,13 +368,13 @@ static int enum_fmt(struct mxc_jpeg_fmt *mxc_formats, int n,
 	return 0;
 }
 
-static struct mxc_jpeg_fmt *mxc_jpeg_find_format(struct mxc_jpeg_ctx *ctx,
-						 u32 pixelformat)
+static const struct mxc_jpeg_fmt *mxc_jpeg_find_format(struct mxc_jpeg_ctx *ctx,
+						       u32 pixelformat)
 {
 	unsigned int k;
 
 	for (k = 0; k < MXC_JPEG_NUM_FORMATS; k++) {
-		struct mxc_jpeg_fmt *fmt = &mxc_formats[k];
+		const struct mxc_jpeg_fmt *fmt = &mxc_formats[k];
 
 		if (fmt->fourcc == pixelformat)
 			return fmt;
@@ -1536,7 +1536,7 @@ static int mxc_jpeg_enum_fmt_vid_out(struct file *file, void *priv,
 				MXC_JPEG_FMT_TYPE_RAW);
 }
 
-static int mxc_jpeg_try_fmt(struct v4l2_format *f, struct mxc_jpeg_fmt *fmt,
+static int mxc_jpeg_try_fmt(struct v4l2_format *f, const struct mxc_jpeg_fmt *fmt,
 			    struct mxc_jpeg_ctx *ctx, int q_type)
 {
 	struct v4l2_pix_format_mplane *pix_mp = &f->fmt.pix_mp;
@@ -1612,7 +1612,7 @@ static int mxc_jpeg_try_fmt_vid_cap(struct file *file, void *priv,
 	struct mxc_jpeg_ctx *ctx = mxc_jpeg_fh_to_ctx(priv);
 	struct mxc_jpeg_dev *jpeg = ctx->mxc_jpeg;
 	struct device *dev = jpeg->dev;
-	struct mxc_jpeg_fmt *fmt;
+	const struct mxc_jpeg_fmt *fmt;
 	u32 fourcc = f->fmt.pix_mp.pixelformat;
 
 	int q_type = (jpeg->mode == MXC_JPEG_DECODE) ?
@@ -1643,7 +1643,7 @@ static int mxc_jpeg_try_fmt_vid_out(struct file *file, void *priv,
 	struct mxc_jpeg_ctx *ctx = mxc_jpeg_fh_to_ctx(priv);
 	struct mxc_jpeg_dev *jpeg = ctx->mxc_jpeg;
 	struct device *dev = jpeg->dev;
-	struct mxc_jpeg_fmt *fmt;
+	const struct mxc_jpeg_fmt *fmt;
 	u32 fourcc = f->fmt.pix_mp.pixelformat;
 
 	int q_type = (jpeg->mode == MXC_JPEG_ENCODE) ?
diff --git a/drivers/media/platform/imx-jpeg/mxc-jpeg.h b/drivers/media/platform/imx-jpeg/mxc-jpeg.h
index 7697de490d2e..4c210852e876 100644
--- a/drivers/media/platform/imx-jpeg/mxc-jpeg.h
+++ b/drivers/media/platform/imx-jpeg/mxc-jpeg.h
@@ -51,7 +51,7 @@ enum mxc_jpeg_mode {
  * @flags:	flags describing format applicability
  */
 struct mxc_jpeg_fmt {
-	char					*name;
+	const char				*name;
 	u32					fourcc;
 	enum v4l2_jpeg_chroma_subsampling	subsampling;
 	int					nc;
@@ -74,14 +74,14 @@ struct mxc_jpeg_desc {
 } __packed;
 
 struct mxc_jpeg_q_data {
-	struct mxc_jpeg_fmt	*fmt;
-	u32			sizeimage[MXC_JPEG_MAX_PLANES];
-	u32			bytesperline[MXC_JPEG_MAX_PLANES];
-	int			w;
-	int			w_adjusted;
-	int			h;
-	int			h_adjusted;
-	unsigned int		sequence;
+	const struct mxc_jpeg_fmt	*fmt;
+	u32				sizeimage[MXC_JPEG_MAX_PLANES];
+	u32				bytesperline[MXC_JPEG_MAX_PLANES];
+	int				w;
+	int				w_adjusted;
+	int				h;
+	int				h_adjusted;
+	unsigned int			sequence;
 };
 
 struct mxc_jpeg_ctx {
-- 
2.32.0