From 676a079fb3be66aed12cf40f236c77b8e7c189c3 Mon Sep 17 00:00:00 2001
From: Douglas Anderson <dianders@chromium.org>
Date: Fri, 17 May 2024 14:36:42 -0700
Subject: [PATCH] drm/panel: himax-hx83102: Check for errors on the NOP in
 prepare()

The mipi_dsi_dcs_nop() function returns an error but we weren't
checking it in hx83102_prepare(). Add a check. This is highly unlikely
to matter in practice. If the NOP failed then likely later MIPI
commands would fail too.

Found by code inspection.

Fixes: 0ef94554dc40 ("drm/panel: himax-hx83102: Break out as separate driver")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20240517143643.7.I3fae28745bf2cacd8dac04d7a06daea50e233f46@changeid
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240517143643.7.I3fae28745bf2cacd8dac04d7a06daea50e233f46@changeid
---
 drivers/gpu/drm/panel/panel-himax-hx83102.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panel/panel-himax-hx83102.c b/drivers/gpu/drm/panel/panel-himax-hx83102.c
index 4ac7f9d8b232b..1ba623e419243 100644
--- a/drivers/gpu/drm/panel/panel-himax-hx83102.c
+++ b/drivers/gpu/drm/panel/panel-himax-hx83102.c
@@ -547,7 +547,11 @@ static int hx83102_prepare(struct drm_panel *panel)
 
 	usleep_range(10000, 11000);
 
-	mipi_dsi_dcs_nop(ctx->dsi);
+	ret = mipi_dsi_dcs_nop(ctx->dsi);
+	if (ret < 0) {
+		dev_err(dev, "Failed to send NOP: %d\n", ret);
+		goto poweroff;
+	}
 	usleep_range(1000, 2000);
 
 	gpiod_set_value(ctx->enable_gpio, 1);
-- 
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