[PATCH v2] backlight: ili922x: fix kernel-doc warnings & notation

[Randy Dunlap]

Convert function-like macro comments to kernel-doc notation and
fix other kernel-doc warnings:

drivers/video/backlight/ili922x.c:85: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
    * START_BYTE(id, rs, rw)
drivers/video/backlight/ili922x.c:118: warning: expecting prototype for CHECK_FREQ_REG(spi_device s, spi_transfer x)(). Prototype was for CHECK_FREQ_REG() instead

ili922x.c:92: warning: contents before sections
ili922x.c:150: warning: No description found for return value of 'ili922x_read_status'
ili922x.c:193: warning: No description found for return value of 'ili922x_read'
ili922x.c:247: warning: No description found for return value of 'ili922x_write'
ili922x.c:353: warning: No description found for return value of 'ili922x_poweron'
ili922x.c:382: warning: No description found for return value of 'ili922x_poweroff'

Fixes: 4cfbfa971478 ("video: backlight: add ili922x lcd driver")
Signed-off-by: Randy Dunlap <rdunlap at infradead.org>
Reported-by: kernel test robot <lkp at intel.com>
Cc: Lee Jones <lee.jones at linaro.org>
Cc: Daniel Thompson <daniel.thompson at linaro.org>
Cc: Jingoo Han <jingoohan1 at gmail.com>
Cc: dri-devel at lists.freedesktop.org
Cc: Stefano Babic <sbabic at denx.de>
Cc: Anatolij Gustschin <agust at denx.de>
---
v2: add periods at end of sentences so that the generated documentation
    flows correctly. (thanks, Daniel)

 drivers/video/backlight/ili922x.c |   29 ++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

--- linux-next-20211115.orig/drivers/video/backlight/ili922x.c
+++ linux-next-20211115/drivers/video/backlight/ili922x.c
@@ -82,13 +82,7 @@
 #define START_RW_READ		1
 
 /**
- * START_BYTE(id, rs, rw)
- *
- * Set the start byte according to the required operation.
- * The start byte is defined as:
- *   ----------------------------------
- *  | 0 | 1 | 1 | 1 | 0 | ID | RS | RW |
- *   ----------------------------------
+ * START_BYTE() - Set the start byte according to the required operation.
  * @id: display's id as set by the manufacturer
  * @rs: operation type bit, one of:
  *	  - START_RS_INDEX	set the index register
@@ -96,14 +90,19 @@
  * @rw: read/write operation
  *	 - START_RW_WRITE	write
  *	 - START_RW_READ	read
+ *
+ * The start byte is defined as:
+ *   ----------------------------------
+ *  | 0 | 1 | 1 | 1 | 0 | ID | RS | RW |
+ *   ----------------------------------
  */
 #define START_BYTE(id, rs, rw)	\
 	(0x70 | (((id) & 0x01) << 2) | (((rs) & 0x01) << 1) | ((rw) & 0x01))
 
 /**
- * CHECK_FREQ_REG(spi_device s, spi_transfer x) - Check the frequency
- *	for the SPI transfer. According to the datasheet, the controller
- *	accept higher frequency for the GRAM transfer, but it requires
+ * CHECK_FREQ_REG() - Check the frequency for the SPI transfer.
+ *	According to the datasheet, the controller
+ *	accepts higher frequency for the GRAM transfer, but it requires
  *	lower frequency when the registers are read/written.
  *	The macro sets the frequency in the spi_transfer structure if
  *	the frequency exceeds the maximum value.
@@ -145,6 +144,8 @@ struct ili922x {
  * ili922x_read_status - read status register from display
  * @spi: spi device
  * @rs:  output value
+ *
+ * Return: %0 on success or a negative error code on failure
  */
 static int ili922x_read_status(struct spi_device *spi, u16 *rs)
 {
@@ -188,6 +189,8 @@ static int ili922x_read_status(struct sp
  * @spi: spi device
  * @reg: offset of the register to be read
  * @rx:  output value
+ *
+ * Return: %0 on success or a negative error code on failure
  */
 static int ili922x_read(struct spi_device *spi, u8 reg, u16 *rx)
 {
@@ -242,6 +245,8 @@ static int ili922x_read(struct spi_devic
  * @spi: struct spi_device *
  * @reg: offset of the register to be written
  * @value: value to be written
+ *
+ * Return: %0 on success or a negative error code on failure
  */
 static int ili922x_write(struct spi_device *spi, u8 reg, u16 value)
 {
@@ -348,6 +353,8 @@ static void set_write_to_gram_reg(struct
  * The sequence to turn on the display is taken from
  * the datasheet and/or the example code provided by the
  * manufacturer.
+ *
+ * Return: %0 on success or a negative value on failure
  */
 static int ili922x_poweron(struct spi_device *spi)
 {
@@ -377,6 +384,8 @@ static int ili922x_poweron(struct spi_de
 /**
  * ili922x_poweroff - turn the display off
  * @spi: spi device
+ *
+ * Return: %0 on success or a negative value on failure
  */
 static int ili922x_poweroff(struct spi_device *spi)
 {