drm/panel/panel-sitronix-st7701: Clean up CMDnBKx selection

There are two command register files, CMD1 and CMD2, where only the CMD2
contains additional register sub-files BK0..3 . Pull the register file
selection call into separate function instead of duplicating it all over
the driver. The CMD2BK2 file is undocumented in datasheet, and is used
for BIST. No functional change.
Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20221014231042.468033-1-marex@denx.de

drivers/gpu/drm/panel/panel-sitronix-st7701.c

@@ -19,6 +19,9 @@
 
 /* Command2 BKx selection command */
 #define DSI_CMD2BKX_SEL			0xFF
+#define DSI_CMD1			0
+#define DSI_CMD2			BIT(4)
+#define DSI_CMD2BK_MASK			GENMASK(3, 0)
 
 /* Command2, BK0 commands */
 #define DSI_CMD2_BK0_PVGAMCTRL		0xB0 /* Positive Voltage Gamma Control */
@@ -39,21 +42,6 @@
 #define DSI_CMD2_BK1_SPD2		0xC2 /* Source EQ2 Setting */
 #define DSI_CMD2_BK1_MIPISET1		0xD0 /* MIPI Setting 1 */
 
-/*
- * Command2 with BK function selection.
- *
- * BIT[4].....CN2
- * BIT[1:0]...BKXSEL
- * 1:00 = CMD2BK0, Command2 BK0
- * 1:01 = CMD2BK1, Command2 BK1
- * 1:11 = CMD2BK3, Command2 BK3
- * 0:00 = Command2 disable
- */
-#define DSI_CMD2BK0_SEL			0x10
-#define DSI_CMD2BK1_SEL			0x11
-#define DSI_CMD2BK3_SEL			0x13
-#define DSI_CMD2BKX_SEL_NONE		0x00
-
 /* Command2, BK0 bytes */
 #define DSI_CMD2_BK0_GAMCTRL_AJ_MASK	GENMASK(7, 6)
 #define DSI_CMD2_BK0_GAMCTRL_VC0_MASK	GENMASK(3, 0)
@@ -191,6 +179,18 @@ static u8 st7701_vgls_map(struct st7701 *st7701)
 	return 0;
 }
 
+static void st7701_switch_cmd_bkx(struct st7701 *st7701, bool cmd2, u8 bkx)
+{
+	u8 val;
+
+	if (cmd2)
+		val = DSI_CMD2 | FIELD_PREP(DSI_CMD2BK_MASK, bkx);
+	else
+		val = DSI_CMD1;
+
+	ST7701_DSI(st7701, DSI_CMD2BKX_SEL, 0x77, 0x01, 0x00, 0x00, val);
+}
+
 static void st7701_init_sequence(struct st7701 *st7701)
 {
 	const struct st7701_panel_desc *desc = st7701->desc;
@@ -208,8 +208,8 @@ static void st7701_init_sequence(struct st7701 *st7701)
 	msleep(st7701->sleep_delay);
 
 	/* Command2, BK0 */
-	ST7701_DSI(st7701, DSI_CMD2BKX_SEL,
-		   0x77, 0x01, 0x00, 0x00, DSI_CMD2BK0_SEL);
+	st7701_switch_cmd_bkx(st7701, true, 0);
+
 	mipi_dsi_dcs_write(st7701->dsi, DSI_CMD2_BK0_PVGAMCTRL,
 			   desc->pv_gamma, ARRAY_SIZE(desc->pv_gamma));
 	mipi_dsi_dcs_write(st7701->dsi, DSI_CMD2_BK0_NVGAMCTRL,
@@ -247,8 +247,7 @@ static void st7701_init_sequence(struct st7701 *st7701)
 			      (clamp((u32)mode->htotal, 512U, 1008U) - 512) / 16));
 
 	/* Command2, BK1 */
-	ST7701_DSI(st7701, DSI_CMD2BKX_SEL,
-			0x77, 0x01, 0x00, 0x00, DSI_CMD2BK1_SEL);
+	st7701_switch_cmd_bkx(st7701, true, 1);
 
 	/* Vop = 3.5375V + (VRHA[7:0] * 0.0125V) */
 	ST7701_DSI(st7701, DSI_CMD2_BK1_VRHS,
@@ -373,33 +372,27 @@ static void dmt028vghmcmi_1a_gip_sequence(struct st7701 *st7701)
 		   0x08, 0x08, 0x08, 0x40,
 			   0x3F, 0x64);
 
-	ST7701_DSI(st7701, DSI_CMD2BKX_SEL,
-		   0x77, 0x01, 0x00, 0x00, DSI_CMD2BKX_SEL_NONE);
+	st7701_switch_cmd_bkx(st7701, false, 0);
 
-	ST7701_DSI(st7701, DSI_CMD2BKX_SEL,
-		   0x77, 0x01, 0x00, 0x00, DSI_CMD2BK3_SEL);
+	st7701_switch_cmd_bkx(st7701, true, 3);
 	ST7701_DSI(st7701, 0xE6, 0x7C);
 	ST7701_DSI(st7701, 0xE8, 0x00, 0x0E);
 
-	ST7701_DSI(st7701, DSI_CMD2BKX_SEL,
-		   0x77, 0x01, 0x00, 0x00, DSI_CMD2BKX_SEL_NONE);
+	st7701_switch_cmd_bkx(st7701, false, 0);
 	ST7701_DSI(st7701, 0x11);
 	msleep(120);
 
-	ST7701_DSI(st7701, DSI_CMD2BKX_SEL,
-		   0x77, 0x01, 0x00, 0x00, DSI_CMD2BK3_SEL);
+	st7701_switch_cmd_bkx(st7701, true, 3);
 	ST7701_DSI(st7701, 0xE8, 0x00, 0x0C);
 	msleep(10);
 	ST7701_DSI(st7701, 0xE8, 0x00, 0x00);
 
-	ST7701_DSI(st7701, DSI_CMD2BKX_SEL,
-		   0x77, 0x01, 0x00, 0x00, DSI_CMD2BKX_SEL_NONE);
+	st7701_switch_cmd_bkx(st7701, false, 0);
 	ST7701_DSI(st7701, 0x11);
 	msleep(120);
 	ST7701_DSI(st7701, 0xE8, 0x00, 0x00);
 
-	ST7701_DSI(st7701, DSI_CMD2BKX_SEL,
-		   0x77, 0x01, 0x00, 0x00, DSI_CMD2BKX_SEL_NONE);
+	st7701_switch_cmd_bkx(st7701, false, 0);
 
 	ST7701_DSI(st7701, 0x3A, 0x70);
 }
@@ -426,8 +419,7 @@ static int st7701_prepare(struct drm_panel *panel)
 		st7701->desc->gip_sequence(st7701);
 
 	/* Disable Command2 */
-	ST7701_DSI(st7701, DSI_CMD2BKX_SEL,
-		   0x77, 0x01, 0x00, 0x00, DSI_CMD2BKX_SEL_NONE);
+	st7701_switch_cmd_bkx(st7701, false, 0);
 
 	return 0;
 }