drm/msm/dsi: move DSI host powerup to modeset time

The DSI subsystem does not fully fall into the pre-enable/enable system
of callbacks, since typically DSI device bridge drivers expect to be
able to communicate with DSI devices at the pre-enable() callback. The
reason is that for some DSI hosts enabling the video stream would
prevent other drivers from sending DSI commands. For example see the
panel-bridge driver, which does drm_panel_prepare() from the
pre_enable() callback (which would be called before our pre_enable()
callback, resulting in panel preparation failures as the link is not yet
ready).

Therewere several attempts to solve this issue, but currently the best
approach is to power up the DSI link from the mode_set() callback,
allowing next bridge/panel to use DSI transfers in the pre_enable()
time. Follow this approach.
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Link: https://lore.kernel.org/r/20211207222901.988484-2-dmitry.baryshkov@linaro.orgSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

drivers/gpu/drm/msm/dsi/dsi_manager.c

@@ -336,13 +336,12 @@ dsi_mgr_connector_best_encoder(struct drm_connector *connector)
 	return msm_dsi_get_encoder(msm_dsi);
 }
 
-static void dsi_mgr_bridge_pre_enable(struct drm_bridge *bridge)
+static void dsi_mgr_bridge_power_on(struct drm_bridge *bridge)
 {
 	int id = dsi_mgr_bridge_get_id(bridge);
 	struct msm_dsi *msm_dsi = dsi_mgr_get_dsi(id);
 	struct msm_dsi *msm_dsi1 = dsi_mgr_get_dsi(DSI_1);
 	struct mipi_dsi_host *host = msm_dsi->host;
-	struct drm_panel *panel = msm_dsi->panel;
 	struct msm_dsi_phy_shared_timings phy_shared_timings[DSI_MAX];
 	bool is_bonded_dsi = IS_BONDED_DSI();
 	int ret;
@@ -383,6 +382,34 @@ static void dsi_mgr_bridge_pre_enable(struct drm_bridge *bridge)
 	if (is_bonded_dsi && msm_dsi1)
 		msm_dsi_host_enable_irq(msm_dsi1->host);
 
+	return;
+
+host1_on_fail:
+	msm_dsi_host_power_off(host);
+host_on_fail:
+	dsi_mgr_phy_disable(id);
+phy_en_fail:
+	return;
+}
+
+static void dsi_mgr_bridge_pre_enable(struct drm_bridge *bridge)
+{
+	int id = dsi_mgr_bridge_get_id(bridge);
+	struct msm_dsi *msm_dsi = dsi_mgr_get_dsi(id);
+	struct msm_dsi *msm_dsi1 = dsi_mgr_get_dsi(DSI_1);
+	struct mipi_dsi_host *host = msm_dsi->host;
+	struct drm_panel *panel = msm_dsi->panel;
+	bool is_bonded_dsi = IS_BONDED_DSI();
+	int ret;
+
+	DBG("id=%d", id);
+	if (!msm_dsi_device_connected(msm_dsi))
+		return;
+
+	/* Do nothing with the host if it is slave-DSI in case of bonded DSI */
+	if (is_bonded_dsi && !IS_MASTER_DSI_LINK(id))
+		return;
+
 	/* Always call panel functions once, because even for dual panels,
 	 * there is only one drm_panel instance.
 	 */
@@ -417,17 +444,7 @@ static void dsi_mgr_bridge_pre_enable(struct drm_bridge *bridge)
 	if (panel)
 		drm_panel_unprepare(panel);
 panel_prep_fail:
-	msm_dsi_host_disable_irq(host);
-	if (is_bonded_dsi && msm_dsi1)
-		msm_dsi_host_disable_irq(msm_dsi1->host);
 
-	if (is_bonded_dsi && msm_dsi1)
-		msm_dsi_host_power_off(msm_dsi1->host);
-host1_on_fail:
-	msm_dsi_host_power_off(host);
-host_on_fail:
-	dsi_mgr_phy_disable(id);
-phy_en_fail:
 	return;
 }
 
@@ -573,6 +590,8 @@ static void dsi_mgr_bridge_mode_set(struct drm_bridge *bridge,
 	msm_dsi_host_set_display_mode(host, adjusted_mode);
 	if (is_bonded_dsi && other_dsi)
 		msm_dsi_host_set_display_mode(other_dsi->host, adjusted_mode);
+
+	dsi_mgr_bridge_power_on(bridge);
 }
 
 static const struct drm_connector_funcs dsi_mgr_connector_funcs = {