media: imx-jpeg: Constify static struct mxc_jpeg_fmt

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>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

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) ?

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 {