drm/bridge: ti-sn65dsi83: Check link status register after enabling the bridge

In rare cases, the bridge may not start up correctly, which usually
leads to no display output. In case this happens, warn about it in
the kernel log.
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Jagan Teki <jagan@amarulasolutions.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Robert Foss <robert.foss@linaro.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220213022648.495895-1-marex@denx.de

drivers/gpu/drm/bridge/ti-sn65dsi83.c

@@ -488,6 +488,11 @@ static void sn65dsi83_atomic_enable(struct drm_bridge *bridge,
 	/* Clear all errors that got asserted during initialization. */
 	regmap_read(ctx->regmap, REG_IRQ_STAT, &pval);
 	regmap_write(ctx->regmap, REG_IRQ_STAT, pval);
+
+	usleep_range(10000, 12000);
+	regmap_read(ctx->regmap, REG_IRQ_STAT, &pval);
+	if (pval)
+		dev_err(ctx->dev, "Unexpected link status 0x%02x\n", pval);
 }
 
 static void sn65dsi83_atomic_disable(struct drm_bridge *bridge,