drm: rcar-du: Fix external clock error checks

The rcar-du driver supports probe deferral for external clocks, but
implements it badly by checking the wrong pointer due to a bad copy and
paste. Fix it.

While at it, reject invalid clocks outright for DU channels that have a
display PLL, as the external clock is mandatory in that case. This
avoids a WARN_ON() at runtime.

Fixes: 1b30dbde8596 ("drm: rcar-du: Add support for external pixel clock")
Reported-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>

diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
index d18a342..79021d7 100644 (file)
--- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
@@ -226,9 +226,6 @@ static void rcar_du_crtc_set_display_timing(struct rcar_du_crtc *rcrtc)
                 * system clock, and have no internal clock divider.
                 */
 
-               if (WARN_ON(!rcrtc->extclock))
-                       return;
-
                /*
                 * The H3 ES1.x exhibits dot clock duty cycle stability issues.
                 * We can work around them by configuring the DPLL to twice the
@@ -1113,9 +1110,16 @@ int rcar_du_crtc_create(struct rcar_du_group *rgrp, unsigned int swindex,
        clk = devm_clk_get(rcdu->dev, clk_name);
        if (!IS_ERR(clk)) {
                rcrtc->extclock = clk;
-       } else if (PTR_ERR(rcrtc->clock) == -EPROBE_DEFER) {
-               dev_info(rcdu->dev, "can't get external clock %u\n", hwindex);
+       } else if (PTR_ERR(clk) == -EPROBE_DEFER) {
                return -EPROBE_DEFER;
+       } else if (rcdu->info->dpll_mask & BIT(hwindex)) {
+               /*
+                * DU channels that have a display PLL can't use the internal
+                * system clock and thus require an external clock.
+                */
+               ret = PTR_ERR(clk);
+               dev_err(rcdu->dev, "can't get dclkin.%u: %d\n", hwindex, ret);
+               return ret;
        }
 
        init_waitqueue_head(&rcrtc->flip_wait);