diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index f42f2bac646623fc1db767bae3a5fff0ecf98aac..4c55cfbad19e95df8cb67864d78af960c073b4df 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -32,8 +32,7 @@ static DEFINE_MUTEX(regmap_debugfs_early_lock);
 /* Calculate the length of a fixed format  */
 static size_t regmap_calc_reg_len(int max_val, char *buf, size_t buf_size)
 {
-	snprintf(buf, buf_size, "%x", max_val);
-	return strlen(buf);
+	return snprintf(NULL, 0, "%x", max_val);
 }
 
 static ssize_t regmap_name_read_file(struct file *file,
@@ -432,7 +431,7 @@ static ssize_t regmap_access_read_file(struct file *file,
 		/* If we're in the region the user is trying to read */
 		if (p >= *ppos) {
 			/* ...but not beyond it */
-			if (buf_pos >= count - 1 - tot_len)
+			if (buf_pos + tot_len + 1 >= count)
 				break;
 
 			/* Format the register */