linux-kernel - [PATCH] host1x: hdmi: Make sure clock is enabled before dumping registers

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Date:	Tue, 30 Jul 2013 11:35:03 +0300
From:	Mikko Perttunen <mperttunen@...dia.com>
To:	<thierry.reding@...il.com>
CC:	<tbergstrom@...dia.com>, <dri-devel@...ts.freedesktop.org>,
	<linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Mikko Perttunen <mperttunen@...dia.com>
Subject: [PATCH] host1x: hdmi: Make sure clock is enabled before dumping registers

The debugfs register dumping function did not enable the HDMI clock.
This led to a possible system hang when reading the debugfs entry
while no HDMI cable was connected to the system. This patch makes
sure that the clock is enabled during the read.

Signed-off-by: Mikko Perttunen <mperttunen@...dia.com>
---
 drivers/gpu/host1x/drm/hdmi.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/host1x/drm/hdmi.c b/drivers/gpu/host1x/drm/hdmi.c
index 01097da..bf7f027 100644
--- a/drivers/gpu/host1x/drm/hdmi.c
+++ b/drivers/gpu/host1x/drm/hdmi.c
@@ -904,6 +904,11 @@ static int tegra_hdmi_show_regs(struct seq_file *s, void *data)
 {
 	struct drm_info_node *node = s->private;
 	struct tegra_hdmi *hdmi = node->info_ent->data;
+	int err;
+
+	err = clk_enable(hdmi->clk);
+	if (err)
+		return err;
 
 #define DUMP_REG(name)						\
 	seq_printf(s, "%-56s %#05x %08lx\n", #name, name,	\
@@ -1069,6 +1074,8 @@ static int tegra_hdmi_show_regs(struct seq_file *s, void *data)
 
 #undef DUMP_REG
 
+	clk_disable(hdmi->clk);
+
 	return 0;
 }
 
-- 
1.8.1.5

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