linux-kernel - [PATCH 2/2] gpu/drm: ingenic: Add workaround for disabled drivers

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Date:   Thu,  5 Aug 2021 21:21:09 +0200
From:   Paul Cercueil <paul@...pouillou.net>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh@...nel.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Sam Ravnborg <sam@...nborg.org>
Cc:     list@...ndingux.net, linux-kernel@...r.kernel.org,
        linux-mips@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        Paul Cercueil <paul@...pouillou.net>
Subject: [PATCH 2/2] gpu/drm: ingenic: Add workaround for disabled drivers

When the drivers of remote devices (e.g. HDMI chip) are disabled in the
config, we want the ingenic-drm driver to be able to probe nonetheless
with the other devices (e.g. internal LCD panel) that are enabled.

Signed-off-by: Paul Cercueil <paul@...pouillou.net>
---
 drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
index d261f7a03b18..5e1fdbb0ba6b 100644
--- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
+++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
@@ -1058,6 +1058,18 @@ static int ingenic_drm_bind(struct device *dev, bool has_components)
 	for (i = 0; ; i++) {
 		ret = drm_of_find_panel_or_bridge(dev->of_node, 0, i, &panel, &bridge);
 		if (ret) {
+			/*
+			 * Workaround for the case where the drivers for the
+			 * remote devices are not enabled. When that happens,
+			 * drm_of_find_panel_or_bridge() returns -EPROBE_DEFER
+			 * endlessly, which prevents the ingenic-drm driver from
+			 * working at all.
+			 */
+			if (ret == -EPROBE_DEFER) {
+				ret = driver_deferred_probe_check_state(dev);
+				if (ret == -ENODEV || ret == -ETIMEDOUT)
+					continue;
+			}
 			if (ret == -ENODEV)
 				break; /* we're done */
 			if (ret != -EPROBE_DEFER)
-- 
2.30.2