drm/mediatek: Separate poweron/poweroff from enable/disable and define new funcs

In order to match the changes of "Use the drm_panel_bridge API",
the poweron/poweroff of dsi is extracted from enable/disable and
defined as new funcs (atomic_pre_enable/atomic_post_disable).

Since dsi_poweron is moved from dsi_enable to pre_enable function, in
order to avoid poweron failure, the operation of dsi register fails to
cause bus hang. Therefore, the protection mechanism is added to the
dsi_enable function.

Fixes: 2dd8075d ("drm/mediatek: mtk_dsi: Use the drm_panel_bridge API")

Link: https://patchwork.kernel.org/project/linux-mediatek/patch/1653012007-11854-3-git-send-email-xinlei.lee@mediatek.com/Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
Signed-off-by: Xinlei Lee <xinlei.lee@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Rex-BC Chen <rex-bc.chen@mediatek.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

drivers/gpu/drm/mediatek/mtk_dsi.c

@@ -691,16 +691,6 @@ static void mtk_dsi_poweroff(struct mtk_dsi *dsi)
 	if (--dsi->refcount != 0)
 		return;
 
-	/*
-	 * mtk_dsi_stop() and mtk_dsi_start() is asymmetric, since
-	 * mtk_dsi_stop() should be called after mtk_drm_crtc_atomic_disable(),
-	 * which needs irq for vblank, and mtk_dsi_stop() will disable irq.
-	 * mtk_dsi_start() needs to be called in mtk_output_dsi_enable(),
-	 * after dsi is fully set.
-	 */
-	mtk_dsi_stop(dsi);
-
-	mtk_dsi_switch_to_cmd_mode(dsi, VM_DONE_INT_FLAG, 500);
 	mtk_dsi_reset_engine(dsi);
 	mtk_dsi_lane0_ulp_mode_enter(dsi);
 	mtk_dsi_clk_ulp_mode_enter(dsi);
@@ -715,17 +705,9 @@ static void mtk_dsi_poweroff(struct mtk_dsi *dsi)
 
 static void mtk_output_dsi_enable(struct mtk_dsi *dsi)
 {
-	int ret;
-
 	if (dsi->enabled)
 		return;
 
-	ret = mtk_dsi_poweron(dsi);
-	if (ret < 0) {
-		DRM_ERROR("failed to power on dsi\n");
-		return;
-	}
-
 	mtk_dsi_set_mode(dsi);
 	mtk_dsi_clk_hs_mode(dsi, 1);
 
@@ -739,7 +721,16 @@ static void mtk_output_dsi_disable(struct mtk_dsi *dsi)
 	if (!dsi->enabled)
 		return;
 
-	mtk_dsi_poweroff(dsi);
+	/*
+	 * mtk_dsi_stop() and mtk_dsi_start() is asymmetric, since
+	 * mtk_dsi_stop() should be called after mtk_drm_crtc_atomic_disable(),
+	 * which needs irq for vblank, and mtk_dsi_stop() will disable irq.
+	 * mtk_dsi_start() needs to be called in mtk_output_dsi_enable(),
+	 * after dsi is fully set.
+	 */
+	mtk_dsi_stop(dsi);
+
+	mtk_dsi_switch_to_cmd_mode(dsi, VM_DONE_INT_FLAG, 500);
 
 	dsi->enabled = false;
 }
@@ -776,13 +767,37 @@ static void mtk_dsi_bridge_atomic_enable(struct drm_bridge *bridge,
 {
 	struct mtk_dsi *dsi = bridge_to_dsi(bridge);
 
+	if (dsi->refcount == 0)
+		return;
+
 	mtk_output_dsi_enable(dsi);
 }
 
+static void mtk_dsi_bridge_atomic_pre_enable(struct drm_bridge *bridge,
+					     struct drm_bridge_state *old_bridge_state)
+{
+	struct mtk_dsi *dsi = bridge_to_dsi(bridge);
+	int ret;
+
+	ret = mtk_dsi_poweron(dsi);
+	if (ret < 0)
+		DRM_ERROR("failed to power on dsi\n");
+}
+
+static void mtk_dsi_bridge_atomic_post_disable(struct drm_bridge *bridge,
+					       struct drm_bridge_state *old_bridge_state)
+{
+	struct mtk_dsi *dsi = bridge_to_dsi(bridge);
+
+	mtk_dsi_poweroff(dsi);
+}
+
 static const struct drm_bridge_funcs mtk_dsi_bridge_funcs = {
 	.attach = mtk_dsi_bridge_attach,
 	.atomic_disable = mtk_dsi_bridge_atomic_disable,
 	.atomic_enable = mtk_dsi_bridge_atomic_enable,
+	.atomic_pre_enable = mtk_dsi_bridge_atomic_pre_enable,
+	.atomic_post_disable = mtk_dsi_bridge_atomic_post_disable,
 	.mode_set = mtk_dsi_bridge_mode_set,
 };