soc/mediatek: Change DSI init commands to take flexible length array

The fixed size of init command in lcm_init_table is wasting lots of
space and we should change to packed array since the command buffer
already provides length information.

With this change, BOE panel init commands have been reduced from 4848
bytes to 1309 bytes.

BUG=b:80501386,b:117254947
TEST=emerge-kukui coreboot chromeos-bootimage; Boots properly

Change-Id: I359dde8e6f2e1c0983f4677193bb47a7ae497ca6
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34778
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/kukui/panel.h

@@ -23,27 +23,28 @@ struct panel_description {
 	struct edid edid;  /* edid info of this panel */
 	enum lb_fb_orientation orientation;  /* panel orientation */
 	void (*power_on)(void);  /* Callback to turn on panel */
-	struct lcm_init_command init[]; /* table of init commands */
+	u8 init[]; /* a packed array of lcm_init_command */
 };
 
 /* Returns the panel description from given ID. */
 extern struct panel_description *get_panel_description(int panel_id);
 
-#define INIT_DCS_CMD(...) { \
-	.cmd = LCM_DCS_CMD, \
-	.len = sizeof((u8[]){__VA_ARGS__}), \
-	.data = {__VA_ARGS__} }
+#define INIT_DCS_CMD(...) \
+	LCM_DCS_CMD, \
+	sizeof((u8[]){__VA_ARGS__}), \
+	__VA_ARGS__
 
-#define INIT_GENERIC_CMD(...) { \
-	.cmd = LCM_GENERIC_CMD, \
-	.len = sizeof((u8[]){__VA_ARGS__}), \
-	.data = {__VA_ARGS__} }
+#define INIT_GENERIC_CMD(...) \
+	LCM_GENERIC_CMD, \
+	sizeof((u8[]){__VA_ARGS__}), \
+	__VA_ARGS__
 
-#define INIT_DELAY_CMD(delay) { \
-	.cmd = LCM_DELAY_CMD,\
-	.len = delay, }
+#define INIT_DELAY_CMD(delay) \
+	LCM_DELAY_CMD, \
+	delay
 
-#define INIT_END_CMD { .cmd = LCM_END_CMD, }
+#define INIT_END_CMD \
+	LCM_END_CMD
 
 /* GPIO names */
 #define GPIO_LCM_RST_1V8		GPIO(LCM_RST)		/* 45 */

src/soc/mediatek/common/dsi.c

@@ -321,12 +321,25 @@ static void mtk_dsi_cmdq(const u8 *data, u8 len, u32 type)
 	}
 }
 
-static void mtk_dsi_send_init_commands(const struct lcm_init_command *init)
+static void mtk_dsi_send_init_commands(const u8 *buf)
 {
-	if (!init)
+	if (!buf)
 		return;
+	const struct lcm_init_command *init = (const void *)buf;
+
+	/*
+	 * The given commands should be in a buffer containing a packed array of
+	 * lcm_init_command and each element may be in variable size so we have
+	 * to parse and scan.
+	 */
+
+	for (; init->cmd != LCM_END_CMD; init = (const void *)buf) {
+		/*
+		 * For some commands like DELAY, the init->len should not be
+		 * counted for buf.
+		 */
+		buf += sizeof(*init);
 
-	for (; init->cmd != LCM_END_CMD; init++) {
 		u32 cmd = init->cmd, len = init->len;
 		u32 type;
 
@@ -374,13 +387,13 @@ static void mtk_dsi_send_init_commands(const struct lcm_init_command *init)
 			return;
 
 		}
-		assert(len <= sizeof(init->data));
+		buf += len;
 		mtk_dsi_cmdq(init->data, len, type);
 	}
 }
 
 int mtk_dsi_init(u32 mode_flags, u32 format, u32 lanes, const struct edid *edid,
-		 const struct lcm_init_command *init_commands)
+		 const u8 *init_commands)
 {
 	int data_rate;
 	u32 bits_per_pixel = mtk_dsi_get_bits_per_pixel(format);

src/soc/mediatek/common/include/soc/dsi_common.h

@@ -350,9 +350,9 @@ struct mtk_phy_timing {
 #define LCM_DCS_CMD 3
 
 struct lcm_init_command {
-	u16 cmd;
-	u16 len;
-	u8 data[8];
+	u8 cmd;
+	u8 len;
+	u8 data[];
 };
 
 /* Functions that each SOC should provide. */
@@ -365,6 +365,6 @@ void mtk_dsi_override_phy_timing(struct mtk_phy_timing *timing);
 /* Public API provided in common/dsi.c */
 int mtk_dsi_bpp_from_format(u32 format);
 int mtk_dsi_init(u32 mode_flags, u32 format, u32 lanes, const struct edid *edid,
-		 const struct lcm_init_command *init_commands);
+		 const u8 *init_commands);
 
 #endif /* SOC_MEDIATEK_DSI_COMMON_H */