linux-kernel - [PATCH] drm/tegra: return with probe defer if GPIO subsystem is not ready

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Date:   Thu, 26 Jul 2018 15:36:06 +0200
From:   Stefan Agner <stefan@...er.ch>
To:     thierry.reding@...il.com, airlied@...ux.ie
Cc:     jonathanh@...dia.com, dri-devel@...ts.freedesktop.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        Stefan Agner <stefan@...er.ch>
Subject: [PATCH] drm/tegra: return with probe defer if GPIO subsystem is not ready

If the GPIO subsystem is not ready make sure to return -EPROBE_DEFER
instead of silently continuing without HPD.

Reported-by: Marcel Ziswiler <marcel.ziswiler@...adex.com>
Signed-off-by: Stefan Agner <stefan@...er.ch>
---
 drivers/gpu/drm/tegra/output.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/tegra/output.c b/drivers/gpu/drm/tegra/output.c
index ffe34bd0bb9d..4bcefe455afd 100644
--- a/drivers/gpu/drm/tegra/output.c
+++ b/drivers/gpu/drm/tegra/output.c
@@ -133,7 +133,9 @@ int tegra_output_probe(struct tegra_output *output)
 	output->hpd_gpio = of_get_named_gpio_flags(output->of_node,
 						   "nvidia,hpd-gpio", 0,
 						   &output->hpd_gpio_flags);
-	if (gpio_is_valid(output->hpd_gpio)) {
+	if (output->hpd_gpio == -EPROBE_DEFER) {
+		return -EPROBE_DEFER;
+	} else if (gpio_is_valid(output->hpd_gpio)) {
 		unsigned long flags;
 
 		err = gpio_request_one(output->hpd_gpio, GPIOF_DIR_IN,
-- 
2.18.0