[PATCH v3] drm/panel: st7703: Fix Panel Initialization for Anbernic RG353V-V2

[Ao Zhong]

This patch addresses an issue with the Anbernic RG353V-V2 panel
initialization that was caused by incorrect parameter. The correct
initialization sequence was derived by referencing the JELOS (Just
Enough Linux OS) BSP kernel's device tree for the V2 panel, which is
identified by the ID "38 21". The relevant device tree can be found at:

https://github.com/JustEnoughLinuxOS/rk356x-kernel/blob/d4d7335a5ca18fc216a29712d5c6cecfb86147d2/arch/arm64/boot/dts/rockchip/rk3568-evb-rg353v.dtsi#L582

The proper initialization sequence was further informed by dissecting
instructions as outlined in the "Rockchip_DRM_Panel_Porting_Guide",
specifically in Chapter 3.3 of the document.

https://web.archive.org/web/20240209211932if_/http://download.t-firefly.com/product/Board/Common/Document/Developer/Rockchip_Developer_Guide_DRM_Panel_Porting_CN.pdf

Upon comparing the initialization sequence within the
rg353v2_init_sequence function against the device tree in the BSP
kernel, discrepancies were identified in two instructions. The relevant
instructions in the device tree are:

1. 15 00 03 b6 7f 7f corresponding to the ST7703_CMD_SETVCOM command
   with parameters 7f 7f
2. 39 00 05 b8 26 62 f0 63 corresponding to the ST7703_CMD_SETPOWER_EXT
   command with parameters 26 62 f0 63

Adjusting the parameters to match those specified in the BSP kernel's
device tree allow the panel to initialize correctly.

Signed-off-by: Ao Zhong <hacc1225 at gmail.com>
---
 drivers/gpu/drm/panel/panel-sitronix-st7703.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-sitronix-st7703.c b/drivers/gpu/drm/panel/panel-sitronix-st7703.c
index b55bafd1a8be..a346d6c3d283 100644
--- a/drivers/gpu/drm/panel/panel-sitronix-st7703.c
+++ b/drivers/gpu/drm/panel/panel-sitronix-st7703.c
@@ -357,8 +357,8 @@ static int rg353v2_init_sequence(struct st7703 *ctx)
 			       0x28, 0x03, 0xff, 0x00, 0x00, 0x00, 0x00);
 	mipi_dsi_dcs_write_seq(dsi, ST7703_CMD_SETCYC, 0x80);
 	mipi_dsi_dcs_write_seq(dsi, ST7703_CMD_SETBGP, 0x0a, 0x0a);
-	mipi_dsi_dcs_write_seq(dsi, ST7703_CMD_SETVCOM, 0x92, 0x92);
-	mipi_dsi_dcs_write_seq(dsi, ST7703_CMD_SETPOWER_EXT, 0x25, 0x22,
+	mipi_dsi_dcs_write_seq(dsi, ST7703_CMD_SETVCOM, 0x7f, 0x7f);
+	mipi_dsi_dcs_write_seq(dsi, ST7703_CMD_SETPOWER_EXT, 0x26, 0x62,
 			       0xf0, 0x63);
 	mipi_dsi_dcs_write_seq(dsi, ST7703_CMD_SETMIPI, 0x33, 0x81, 0x05,
 			       0xf9, 0x0e, 0x0e, 0x20, 0x00, 0x00, 0x00, 0x00,
-- 
2.43.0