drm/panel: mantix: Improve power off sequence

According to the sequence from section 7.3.4 of FT8006P datasheet,
TP_RSTN and RESX should be asserted after disabling AVDD and AVEE and
together with VDDI.

Also, AVEE power down needs to happen at least 150ms after entering
sleep mode.

Signed-off-by: Sebastian Krzyszkowiak <sebastian.krzyszkowiak@puri.sm>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patch.msgid.link/20260105-mantix-halo-fixes-v1-3-1ebc9b195a34@puri.sm

Author: dos1

drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c

@@ -96,22 +96,26 @@ static int mantix_disable(struct drm_panel *panel)
 	mipi_dsi_dcs_set_display_off_multi(&dsi_ctx);
 	mipi_dsi_dcs_enter_sleep_mode_multi(&dsi_ctx);
 
+	/* T10 */
+	mipi_dsi_msleep(&dsi_ctx, 150);
+
 	return dsi_ctx.accum_err;
 }
 
 static int mantix_unprepare(struct drm_panel *panel)
 {
 	struct mantix *ctx = panel_to_mantix(panel);
 
-	gpiod_set_value_cansleep(ctx->tp_rstn_gpio, 1);
-	usleep_range(5000, 6000);
-	gpiod_set_value_cansleep(ctx->reset_gpio, 1);
-
 	regulator_disable(ctx->avee);
 	regulator_disable(ctx->avdd);
 	/* T11 */
 	usleep_range(5000, 6000);
 	regulator_disable(ctx->vddi);
+
+	gpiod_set_value_cansleep(ctx->tp_rstn_gpio, 1);
+	usleep_range(5000, 6000);
+	gpiod_set_value_cansleep(ctx->reset_gpio, 1);
+
 	/* T14 */
 	msleep(50);