drm/panel: boe-himax8279d: Don't call unprepare+disable at shutdown/remove

It's the responsibility of a correctly written DRM modeset driver to
call drm_atomic_helper_shutdown() at shutdown time and that should be
disabling / unpreparing the panel if needed. Panel drivers shouldn't
be calling these functions themselves.

A recent effort was made to fix as many DRM modeset drivers as
possible [1] [2] [3] and most drivers are fixed now.

Unfortunately, grepping mainline for this panel's compatible string
shows no hits, so we can't be 100% sure if the DRM modeset driver used
with this panel has been fixed. If it is found that the DRM modeset
driver hasn't been fixed then this patch could be temporarily reverted
until it is.

[1] https://lore.kernel.org/r/20230901234015.566018-1-dianders@chromium.org
[2] https://lore.kernel.org/r/20230901234202.566951-1-dianders@chromium.org
[3] https://lore.kernel.org/r/20230921192749.1542462-1-dianders@chromium.org

Cc: Jerry Han <jerry.han.hq@gmail.com>
Cc: Jitao Shi <jitao.shi@mediatek.com>
Cc: Rock Wang <rock_wang@himax.com.cn>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20240604172305.v3.2.I19086c524d38f28f746befe85cb39ffda9d2f666@changeidSigned-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240604172305.v3.2.I19086c524d38f28f746befe85cb39ffda9d2f666@changeid

drivers/gpu/drm/panel/panel-boe-himax8279d.c

@@ -894,14 +894,6 @@ static void panel_remove(struct mipi_dsi_device *dsi)
 	struct panel_info *pinfo = mipi_dsi_get_drvdata(dsi);
 	int err;
 
-	err = drm_panel_disable(&pinfo->base);
-	if (err < 0)
-		dev_err(&dsi->dev, "failed to disable panel: %d\n", err);
-
-	err = drm_panel_unprepare(&pinfo->base);
-	if (err < 0)
-		dev_err(&dsi->dev, "failed to unprepare panel: %d\n", err);
-
 	err = mipi_dsi_detach(dsi);
 	if (err < 0)
 		dev_err(&dsi->dev, "failed to detach from DSI host: %d\n", err);
@@ -909,14 +901,6 @@ static void panel_remove(struct mipi_dsi_device *dsi)
 	drm_panel_remove(&pinfo->base);
 }
 
-static void panel_shutdown(struct mipi_dsi_device *dsi)
-{
-	struct panel_info *pinfo = mipi_dsi_get_drvdata(dsi);
-
-	drm_panel_disable(&pinfo->base);
-	drm_panel_unprepare(&pinfo->base);
-}
-
 static struct mipi_dsi_driver panel_driver = {
 	.driver = {
 		.name = "panel-boe-himax8279d",
@@ -924,7 +908,6 @@ static struct mipi_dsi_driver panel_driver = {
 	},
 	.probe = panel_probe,
 	.remove = panel_remove,
-	.shutdown = panel_shutdown,
 };
 module_mipi_dsi_driver(panel_driver);