[PATCH 1/9] drm: rcar-du: Fix crash when using LVDS1 clock for CRTC

[Laurent Pinchart]

On D3 and E3 platforms, the LVDS encoder includes a PLL that can
generate a clock for the corresponding CRTC, used even when the CRTC
output to a non-LVDS port. This mechanism is supported by the driver,
but the implementation is broken in dual-link LVDS mode. In that case,
the LVDS1 drm_encoder is skipped, which causes a crash when trying to
access its bridge later on.

Fix this by storing bridge pointers internally instead of retrieving
them from the encoder.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas at ideasonboard.com>
---
 drivers/gpu/drm/rcar-du/rcar_du_crtc.c    | 10 ++--------
 drivers/gpu/drm/rcar-du/rcar_du_drv.h     |  3 +++
 drivers/gpu/drm/rcar-du/rcar_du_encoder.c |  4 ++++
 3 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
index b5fb941e0f53..e23b9c7b4afe 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
@@ -730,13 +730,10 @@ static void rcar_du_crtc_atomic_enable(struct drm_crtc *crtc,
 	 */
 	if (rcdu->info->lvds_clk_mask & BIT(rcrtc->index) &&
 	    rstate->outputs == BIT(RCAR_DU_OUTPUT_DPAD0)) {
-		struct rcar_du_encoder *encoder =
-			rcdu->encoders[RCAR_DU_OUTPUT_LVDS0 + rcrtc->index];
+		struct drm_bridge *bridge = rcdu->lvds[rcrtc->index];
 		const struct drm_display_mode *mode =
 			&crtc->state->adjusted_mode;
-		struct drm_bridge *bridge;
 
-		bridge = drm_bridge_chain_get_first_bridge(&encoder->base);
 		rcar_lvds_clk_enable(bridge, mode->clock * 1000);
 	}
 
@@ -764,15 +761,12 @@ static void rcar_du_crtc_atomic_disable(struct drm_crtc *crtc,
 
 	if (rcdu->info->lvds_clk_mask & BIT(rcrtc->index) &&
 	    rstate->outputs == BIT(RCAR_DU_OUTPUT_DPAD0)) {
-		struct rcar_du_encoder *encoder =
-			rcdu->encoders[RCAR_DU_OUTPUT_LVDS0 + rcrtc->index];
-		struct drm_bridge *bridge;
+		struct drm_bridge *bridge = rcdu->lvds[rcrtc->index];
 
 		/*
 		 * Disable the LVDS clock output, see
 		 * rcar_du_crtc_atomic_enable().
 		 */
-		bridge = drm_bridge_chain_get_first_bridge(&encoder->base);
 		rcar_lvds_clk_disable(bridge);
 	}
 
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_drv.h b/drivers/gpu/drm/rcar-du/rcar_du_drv.h
index 61504c54e2ec..71732fc5df8f 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_drv.h
+++ b/drivers/gpu/drm/rcar-du/rcar_du_drv.h
@@ -20,6 +20,7 @@
 
 struct clk;
 struct device;
+struct drm_bridge;
 struct drm_device;
 struct drm_property;
 struct rcar_du_device;
@@ -71,6 +72,7 @@ struct rcar_du_device_info {
 #define RCAR_DU_MAX_CRTCS		4
 #define RCAR_DU_MAX_GROUPS		DIV_ROUND_UP(RCAR_DU_MAX_CRTCS, 2)
 #define RCAR_DU_MAX_VSPS		4
+#define RCAR_DU_MAX_LVDS		2
 
 struct rcar_du_device {
 	struct device *dev;
@@ -88,6 +90,7 @@ struct rcar_du_device {
 	struct rcar_du_group groups[RCAR_DU_MAX_GROUPS];
 	struct platform_device *cmms[RCAR_DU_MAX_CRTCS];
 	struct rcar_du_vsp vsps[RCAR_DU_MAX_VSPS];
+	struct drm_bridge *lvds[RCAR_DU_MAX_LVDS];
 
 	struct {
 		struct drm_property *colorkey;
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_encoder.c b/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
index b0335da0c161..2d40da98144b 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
@@ -91,6 +91,10 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
 			ret = -EPROBE_DEFER;
 			goto done;
 		}
+
+		if (output == RCAR_DU_OUTPUT_LVDS0 ||
+		    output == RCAR_DU_OUTPUT_LVDS1)
+			rcdu->lvds[output - RCAR_DU_OUTPUT_LVDS0] = bridge;
 	}
 
 	/*
-- 
Regards,

Laurent Pinchart