linux-kernel - [PATCH 1/1] regmap: debugfs: runtime resume a device when reading registers

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Date: Wed, 10 Jan 2024 10:53:58 +0100
From: Alexander Stein <alexander.stein@...tq-group.com>
To: Mark Brown <broonie@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J . Wysocki" <rafael@...nel.org>
Cc: Alexander Stein <alexander.stein@...tq-group.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/1] regmap: debugfs: runtime resume a device when reading registers

If the registers shall be read from device, runtime resume it in order
to enable a possiblly attached power domain before accessing the device.

Signed-off-by: Alexander Stein <alexander.stein@...tq-group.com>
---
 drivers/base/regmap/regmap-debugfs.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index fb84cda92a753..063ede23173af 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -12,6 +12,7 @@
 #include <linux/uaccess.h>
 #include <linux/device.h>
 #include <linux/list.h>
+#include <linux/pm_runtime.h>
 
 #include "internal.h"
 
@@ -233,6 +234,10 @@ static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
 	if (!buf)
 		return -ENOMEM;
 
+	ret = pm_runtime_resume_and_get(map->dev);
+	if (ret)
+		goto out_free;
+
 	regmap_calc_tot_len(map, buf, count);
 
 	/* Work out which register we're starting at */
@@ -277,6 +282,8 @@ static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
 	*ppos += buf_pos;
 
 out:
+	pm_runtime_put(map->dev);
+out_free:
 	kfree(buf);
 	return ret;
 }
-- 
2.34.1