drm/udl: Add constants for commands

Add constants for the various commands that the driver can send to
the device and update the respective helper functions. No functional
changes.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221006095355.23579-17-tzimmermann@suse.de

drivers/gpu/drm/udl/udl_drv.h

@@ -102,14 +102,4 @@ int udl_render_hline(struct drm_device *dev, int log_bpp, struct urb **urb_ptr,
 int udl_drop_usb(struct drm_device *dev);
 int udl_select_std_channel(struct udl_device *udl);
 
-#define CMD_WRITE_RAW8   "\xAF\x60" /**< 8 bit raw write command. */
-#define CMD_WRITE_RL8    "\xAF\x61" /**< 8 bit run length command. */
-#define CMD_WRITE_COPY8  "\xAF\x62" /**< 8 bit copy command. */
-#define CMD_WRITE_RLX8   "\xAF\x63" /**< 8 bit extended run length command. */
-
-#define CMD_WRITE_RAW16  "\xAF\x68" /**< 16 bit raw write command. */
-#define CMD_WRITE_RL16   "\xAF\x69" /**< 16 bit run length command. */
-#define CMD_WRITE_COPY16 "\xAF\x6A" /**< 16 bit copy command. */
-#define CMD_WRITE_RLX16  "\xAF\x6B" /**< 16 bit extended run length command. */
-
 #endif

drivers/gpu/drm/udl/udl_modeset.c

@@ -29,15 +29,17 @@
 #include "udl_proto.h"
 
 /*
- * All DisplayLink bulk operations start with 0xAF, followed by specific code
+ * All DisplayLink bulk operations start with 0xaf (UDL_MSG_BULK), followed by
- * All operations are written to buffers which then later get sent to device
+ * a specific command code. All operations are written to a command buffer, which
+ * the driver sends to the device.
  */
 static char *udl_set_register(char *buf, u8 reg, u8 val)
 {
-	*buf++ = 0xAF;
+	*buf++ = UDL_MSG_BULK;
-	*buf++ = 0x20;
+	*buf++ = UDL_CMD_WRITEREG;
 	*buf++ = reg;
 	*buf++ = val;
+
 	return buf;
 }
 
@@ -179,8 +181,8 @@ static char *udl_set_display_mode(char *buf, struct drm_display_mode *mode)
 
 static char *udl_dummy_render(char *wrptr)
 {
-	*wrptr++ = 0xAF;
+	*wrptr++ = UDL_MSG_BULK;
-	*wrptr++ = 0x6A; /* copy */
+	*wrptr++ = UDL_CMD_WRITECOPY16;
 	*wrptr++ = 0x00; /* from addr */
 	*wrptr++ = 0x00;
 	*wrptr++ = 0x00;
@@ -235,7 +237,7 @@ static int udl_handle_damage(struct drm_framebuffer *fb,
 		/* Send partial buffer remaining before exiting */
 		int len;
 		if (cmd < (char *)urb->transfer_buffer + urb->transfer_buffer_length)
-			*cmd++ = 0xAF;
+			*cmd++ = UDL_MSG_BULK;
 		len = cmd - (char *)urb->transfer_buffer;
 		ret = udl_submit_urb(dev, urb, len);
 	} else {

drivers/gpu/drm/udl/udl_proto.h

@@ -5,6 +5,21 @@
 
 #include <linux/bits.h>
 
+#define UDL_MSG_BULK		0xaf
+
+/* Register access */
+#define UDL_CMD_WRITEREG	0x20 /* See register constants below */
+
+/* Framebuffer access */
+#define UDL_CMD_WRITERAW8	0x60 /* 8 bit raw write command. */
+#define UDL_CMD_WRITERL8	0x61 /* 8 bit run length command. */
+#define UDL_CMD_WRITECOPY8	0x62 /* 8 bit copy command. */
+#define UDL_CMD_WRITERLX8	0x63 /* 8 bit extended run length command. */
+#define UDL_CMD_WRITERAW16	0x68 /* 16 bit raw write command. */
+#define UDL_CMD_WRITERL16	0x69 /* 16 bit run length command. */
+#define UDL_CMD_WRITECOPY16	0x6a /* 16 bit copy command. */
+#define UDL_CMD_WRITERLX16	0x6b /* 16 bit extended run length command. */
+
 /* Color depth */
 #define UDL_REG_COLORDEPTH		0x00
 #define UDL_COLORDEPTH_16BPP		0

drivers/gpu/drm/udl/udl_transfer.c

@@ -10,6 +10,7 @@
 #include <asm/unaligned.h>
 
 #include "udl_drv.h"
+#include "udl_proto.h"
 
 #define MAX_CMD_PIXELS		255
 
@@ -89,8 +90,8 @@ static void udl_compress_hline16(
 		const u8 *cmd_pixel_start, *cmd_pixel_end = NULL;
 		uint16_t pixel_val16;
 
-		*cmd++ = 0xaf;
+		*cmd++ = UDL_MSG_BULK;
-		*cmd++ = 0x6b;
+		*cmd++ = UDL_CMD_WRITERLX16;
 		*cmd++ = (uint8_t) ((dev_addr >> 16) & 0xFF);
 		*cmd++ = (uint8_t) ((dev_addr >> 8) & 0xFF);
 		*cmd++ = (uint8_t) ((dev_addr) & 0xFF);
@@ -152,7 +153,7 @@ static void udl_compress_hline16(
 	if (cmd_buffer_end <= MIN_RLX_CMD_BYTES + cmd) {
 		/* Fill leftover bytes with no-ops */
 		if (cmd_buffer_end > cmd)
-			memset(cmd, 0xAF, cmd_buffer_end - cmd);
+			memset(cmd, UDL_MSG_BULK, cmd_buffer_end - cmd);
 		cmd = (uint8_t *) cmd_buffer_end;
 	}