video/hdmi: Constify 'buffer' to the unpack functions

The unpack functions just read from the passed in buffer,
so make it const.

Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Hans Verkuil <hans.verkuil@cisco.com>
Cc: linux-media@vger.kernel.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180920185145.1912-2-ville.syrjala@linux.intel.com
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>

drivers/video/hdmi.c

@@ -31,7 +31,7 @@
 
 #define hdmi_log(fmt, ...) dev_printk(level, dev, fmt, ##__VA_ARGS__)
 
-static u8 hdmi_infoframe_checksum(u8 *ptr, size_t size)
+static u8 hdmi_infoframe_checksum(const u8 *ptr, size_t size)
 {
 	u8 csum = 0;
 	size_t i;
@@ -1016,9 +1016,9 @@ EXPORT_SYMBOL(hdmi_infoframe_log);
  * Returns 0 on success or a negative error code on failure.
  */
 static int hdmi_avi_infoframe_unpack(struct hdmi_avi_infoframe *frame,
-				     void *buffer)
+				     const void *buffer)
 {
-	u8 *ptr = buffer;
+	const u8 *ptr = buffer;
 	int ret;
 
 	if (ptr[0] != HDMI_INFOFRAME_TYPE_AVI ||
@@ -1079,9 +1079,9 @@ static int hdmi_avi_infoframe_unpack(struct hdmi_avi_infoframe *frame,
  * Returns 0 on success or a negative error code on failure.
  */
 static int hdmi_spd_infoframe_unpack(struct hdmi_spd_infoframe *frame,
-				     void *buffer)
+				     const void *buffer)
 {
-	u8 *ptr = buffer;
+	const u8 *ptr = buffer;
 	int ret;
 
 	if (ptr[0] != HDMI_INFOFRAME_TYPE_SPD ||
@@ -1117,9 +1117,9 @@ static int hdmi_spd_infoframe_unpack(struct hdmi_spd_infoframe *frame,
  * Returns 0 on success or a negative error code on failure.
  */
 static int hdmi_audio_infoframe_unpack(struct hdmi_audio_infoframe *frame,
-				       void *buffer)
+				       const void *buffer)
 {
-	u8 *ptr = buffer;
+	const u8 *ptr = buffer;
 	int ret;
 
 	if (ptr[0] != HDMI_INFOFRAME_TYPE_AUDIO ||
@@ -1163,9 +1163,9 @@ static int hdmi_audio_infoframe_unpack(struct hdmi_audio_infoframe *frame,
  */
 static int
 hdmi_vendor_any_infoframe_unpack(union hdmi_vendor_any_infoframe *frame,
-				 void *buffer)
+				 const void *buffer)
 {
-	u8 *ptr = buffer;
+	const u8 *ptr = buffer;
 	size_t length;
 	int ret;
 	u8 hdmi_video_format;
@@ -1234,10 +1234,11 @@ hdmi_vendor_any_infoframe_unpack(union hdmi_vendor_any_infoframe *frame,
  *
  * Returns 0 on success or a negative error code on failure.
  */
-int hdmi_infoframe_unpack(union hdmi_infoframe *frame, void *buffer)
+int hdmi_infoframe_unpack(union hdmi_infoframe *frame,
+			  const void *buffer)
 {
 	int ret;
-	u8 *ptr = buffer;
+	const u8 *ptr = buffer;
 
 	switch (ptr[0]) {
 	case HDMI_INFOFRAME_TYPE_AVI:

include/linux/hdmi.h

@@ -332,7 +332,8 @@ union hdmi_infoframe {
 
 ssize_t
 hdmi_infoframe_pack(union hdmi_infoframe *frame, void *buffer, size_t size);
-int hdmi_infoframe_unpack(union hdmi_infoframe *frame, void *buffer);
+int hdmi_infoframe_unpack(union hdmi_infoframe *frame,
+			  const void *buffer);
 void hdmi_infoframe_log(const char *level, struct device *dev,
 			union hdmi_infoframe *frame);