drm/panel: novatek-nt36672a: 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.

A grep through mainline for compatible strings used by this driver
indicates that it is used by Qualcomm boards. The Qualcomm driver
appears to be correctly calling drm_atomic_helper_shutdown() so we can
remove the calls.

[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: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Benni Steini <bennisteinir@gmail.com>
Cc: Marijn Suijten <marijn.suijten@somainline.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Maxime Ripard <mripard@kernel.org>
Tested-by: Joel Selvaraj <jo@jsfamily.in>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240503143327.RFT.v2.19.I67819ba5513d4ef85f254a68b22a3402b4cdf30f@changeid

drivers/gpu/drm/panel/panel-novatek-nt36672a.c

@@ -656,14 +656,6 @@ static void nt36672a_panel_remove(struct mipi_dsi_device *dsi)
 	struct nt36672a_panel *pinfo = mipi_dsi_get_drvdata(dsi);
 	int err;
 
-	err = drm_panel_unprepare(&pinfo->base);
-	if (err < 0)
-		dev_err(&dsi->dev, "failed to unprepare panel: %d\n", err);
-
-	err = drm_panel_disable(&pinfo->base);
-	if (err < 0)
-		dev_err(&dsi->dev, "failed to disable 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);
@@ -671,14 +663,6 @@ static void nt36672a_panel_remove(struct mipi_dsi_device *dsi)
 	drm_panel_remove(&pinfo->base);
 }
 
-static void nt36672a_panel_shutdown(struct mipi_dsi_device *dsi)
-{
-	struct nt36672a_panel *pinfo = mipi_dsi_get_drvdata(dsi);
-
-	drm_panel_disable(&pinfo->base);
-	drm_panel_unprepare(&pinfo->base);
-}
-
 static const struct of_device_id tianma_fhd_video_of_match[] = {
 	{ .compatible = "tianma,fhd-video", .data = &tianma_fhd_video_panel_desc },
 	{ },
@@ -692,7 +676,6 @@ static struct mipi_dsi_driver nt36672a_panel_driver = {
 	},
 	.probe = nt36672a_panel_probe,
 	.remove = nt36672a_panel_remove,
-	.shutdown = nt36672a_panel_shutdown,
 };
 module_mipi_dsi_driver(nt36672a_panel_driver);