[PATCH v2] drm/panel: nt35510: Make new commands optional

[Linus Walleij]

The commit introducing the Frida display started to write the
SETVCMOFF registers unconditionally, and some (not all!) Hydis
display seem to be affected by ghosting after the commit.

Make SETVCMOFF optional and only send these commands on the
Frida display for now.

Reported-by: Stefan Hansson <newbyte at postmarketos.org>
Fixes: 219a1f49094f ("drm/panel: nt35510: support FRIDA FRD400B25025-A-CTK")
Acked-by: Jessica Zhang <quic_jesszhan at quicinc.com>
Signed-off-by: Linus Walleij <linus.walleij at linaro.org>
---
Changes in v2:
- After Stefan's testing conclude that we only need to make
  SETVCMOFF optional.
- Link to v1: https://lore.kernel.org/r/20240906-fix-nt35510-v1-1-1971f3af7dda@linaro.org
---
 drivers/gpu/drm/panel/panel-novatek-nt35510.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-novatek-nt35510.c b/drivers/gpu/drm/panel/panel-novatek-nt35510.c
index d3bfdfc9cff6..a3460ed38cc4 100644
--- a/drivers/gpu/drm/panel/panel-novatek-nt35510.c
+++ b/drivers/gpu/drm/panel/panel-novatek-nt35510.c
@@ -38,6 +38,7 @@
 
 #define NT35510_CMD_CORRECT_GAMMA BIT(0)
 #define NT35510_CMD_CONTROL_DISPLAY BIT(1)
+#define NT35510_CMD_SETVCMOFF BIT(2)
 
 #define MCS_CMD_MAUCCTR		0xF0 /* Manufacturer command enable */
 #define MCS_CMD_READ_ID1	0xDA
@@ -675,16 +676,19 @@ static int nt35510_setup_power(struct nt35510 *nt)
 				nt->conf->bt2ctr);
 	if (ret)
 		return ret;
+
 	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETVCL,
 				NT35510_P1_VCL_LEN,
 				nt->conf->vcl);
 	if (ret)
 		return ret;
+
 	ret = nt35510_send_long(nt, dsi, NT35510_P1_BT3CTR,
 				NT35510_P1_BT3CTR_LEN,
 				nt->conf->bt3ctr);
 	if (ret)
 		return ret;
+
 	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETVGH,
 				NT35510_P1_VGH_LEN,
 				nt->conf->vgh);
@@ -721,11 +725,13 @@ static int nt35510_setup_power(struct nt35510 *nt)
 	if (ret)
 		return ret;
 
-	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETVCMOFF,
-				NT35510_P1_VCMOFF_LEN,
-				nt->conf->vcmoff);
-	if (ret)
-		return ret;
+	if (nt->conf->cmds & NT35510_CMD_SETVCMOFF) {
+		ret = nt35510_send_long(nt, dsi, NT35510_P1_SETVCMOFF,
+					NT35510_P1_VCMOFF_LEN,
+					nt->conf->vcmoff);
+		if (ret)
+			return ret;
+	}
 
 	/* Typically 10 ms */
 	usleep_range(10000, 20000);
@@ -1319,7 +1325,7 @@ static const struct nt35510_config nt35510_frida_frd400b25025 = {
 	},
 	.mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
 			MIPI_DSI_MODE_LPM,
-	.cmds = NT35510_CMD_CONTROL_DISPLAY,
+	.cmds = NT35510_CMD_CONTROL_DISPLAY | NT35510_CMD_SETVCMOFF,
 	/* 0x03: AVDD = 6.2V */
 	.avdd = { 0x03, 0x03, 0x03 },
 	/* 0x46: PCK = 2 x Hsync, BTP = 2.5 x VDDB */

---
base-commit: 8400291e289ee6b2bf9779ff1c83a291501f017b
change-id: 20240906-fix-nt35510-a8ec6e47e036

Best regards,
-- 
Linus Walleij <linus.walleij at linaro.org>