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

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
index c2afef97c2b2a2829a72aa3afe82e908b6de2b34..2831f0813c3a8cd0bf9776045c029d418cfa0e1a 100644 (file)
--- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
+++ b/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,