[PATCH 4/4] drm/panel: newvision-nv3051d: Use mipi_dsi_*_multi(); fix minor bugs

[Akash Sukhavasi <akash.sukhavasi@gmail.com>]

The mipi_dsi_dcs_*() functions used by this driver are deprecated in
favour of their _multi() counterparts, as noted in
Documentation/gpu/todo.rst. The _multi() variants record the first
error in a context structure and skip subsequent calls once an error
is set, removing the need to check the return value after each command.
They also log failures internally, making the per-call dev_err() calls
redundant.

Convert prepare() and unprepare() to use the _multi() equivalents.

In prepare(), use mipi_dsi_msleep() and mipi_dsi_usleep_range() instead
of plain msleep()/usleep_range() for delays between DSI commands, so
they are skipped on prior error since the function will clean up via the
existing disable_vdd label anyway.

In unprepare(), keep plain msleep() and usleep_range() since the
hardware delays must execute regardless of any prior DSI error. The
original code logged a set_display_off() failure and still attempted
enter_sleep_mode(), so clear accum_err after set_display_off_multi()
to keep that behaviour.

This also fixes a bug where a failure in enter_sleep_mode would return
early, skipping the post-sleep delay, reset GPIO assertion, and
regulator disable, leaving the panel stuck in a prepared state. Because
drm_panel_unprepare() does not clear panel->prepared when the callback
returns an error, drm_panel_prepare() would return early on the next
call, leaving the panel unable to be re-initialised.

Cc: Chris Morgan <macromorgan@hotmail.com>
Signed-off-by: Akash Sukhavasi <akash.sukhavasi@gmail.com>
---
Compile tested only, no hardware available. checkpatch and a W=1
build are clean.
---
 drivers/gpu/drm/panel/panel-newvision-nv3051d.c | 36 +++++++++----------------
 1 file changed, 13 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-newvision-nv3051d.c b/drivers/gpu/drm/panel/panel-newvision-nv3051d.c
index 22560384e48e..7dc25102a773 100644
--- a/drivers/gpu/drm/panel/panel-newvision-nv3051d.c
+++ b/drivers/gpu/drm/panel/panel-newvision-nv3051d.c
@@ -247,19 +247,14 @@ static int panel_nv3051d_unprepare(struct drm_panel *panel)
 {
 	struct panel_nv3051d *ctx = panel_to_panelnv3051d(panel);
 	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
-	int ret;
-
-	ret = mipi_dsi_dcs_set_display_off(dsi);
-	if (ret < 0)
-		dev_err(ctx->dev, "failed to set display off: %d\n", ret);
+	struct mipi_dsi_multi_context dsi_ctx = { .dsi = dsi };
 
+	mipi_dsi_dcs_set_display_off_multi(&dsi_ctx);
+	/* Reset error to continue power-down sequence even if display off failed */
+	dsi_ctx.accum_err = 0;
 	msleep(20);
-
-	ret = mipi_dsi_dcs_enter_sleep_mode(dsi);
-	if (ret < 0) {
-		dev_err(ctx->dev, "failed to enter sleep mode: %d\n", ret);
-		return ret;
-	}
+	/* Enter sleep mode; error does not prevent power-off */
+	mipi_dsi_dcs_enter_sleep_mode_multi(&dsi_ctx);
 
 	usleep_range(10000, 15000);
 
@@ -274,6 +269,7 @@ static int panel_nv3051d_prepare(struct drm_panel *panel)
 {
 	struct panel_nv3051d *ctx = panel_to_panelnv3051d(panel);
 	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
+	struct mipi_dsi_multi_context dsi_ctx = { .dsi = dsi };
 	int ret;
 
 	dev_dbg(ctx->dev, "Resetting the panel\n");
@@ -295,22 +291,16 @@ static int panel_nv3051d_prepare(struct drm_panel *panel)
 		goto disable_vdd;
 	}
 
-	ret = mipi_dsi_dcs_exit_sleep_mode(dsi);
-	if (ret < 0) {
-		dev_err(ctx->dev, "Failed to exit sleep mode: %d\n", ret);
-		goto disable_vdd;
-	}
-
-	msleep(200);
+	mipi_dsi_dcs_exit_sleep_mode_multi(&dsi_ctx);
+	mipi_dsi_msleep(&dsi_ctx, 200);
+	mipi_dsi_dcs_set_display_on_multi(&dsi_ctx);
+	mipi_dsi_usleep_range(&dsi_ctx, 10000, 15000);
 
-	ret = mipi_dsi_dcs_set_display_on(dsi);
-	if (ret < 0) {
-		dev_err(ctx->dev, "Failed to set display on: %d\n", ret);
+	if (dsi_ctx.accum_err) {
+		ret = dsi_ctx.accum_err;
 		goto disable_vdd;
 	}
 
-	usleep_range(10000, 15000);
-
 	return 0;
 
 disable_vdd:

-- 
2.56.0