linux-kernel - [RFC PATCH v2 1/2] block: bsg: resume platform device before accessing

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Message-Id: <b1db5394aa3f6cf44cd9adb9c8d569caa0c9e4f5.1611803264.git.asutoshd@codeaurora.org>
Date:   Wed, 27 Jan 2021 19:26:37 -0800
From:   Asutosh Das <asutoshd@...eaurora.org>
To:     cang@...eaurora.org, martin.petersen@...cle.com,
        linux-scsi@...r.kernel.org
Cc:     Asutosh Das <asutoshd@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, stern@...land.harvard.edu,
        "Bao D . Nguyen" <nguyenb@...eaurora.org>,
        FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>,
        Jens Axboe <axboe@...nel.dk>,
        linux-block@...r.kernel.org (open list:BLOCK LAYER),
        linux-kernel@...r.kernel.org (open list)
Subject: [RFC PATCH v2 1/2] block: bsg: resume platform device before accessing

It may happen that the underlying device's runtime-pm is
not controlled by block-pm. So it's possible that when
commands are sent to the device, it's suspended and may not
be resumed by blk-pm. Hence explicitly resume the parent
which is the platform device.

Signed-off-by: Asutosh Das <asutoshd@...eaurora.org>
Signed-off-by: Can Guo <cang@...eaurora.org>
Signed-off-by: Bao D. Nguyen <nguyenb@...eaurora.org>
---
 block/bsg.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/block/bsg.c b/block/bsg.c
index d7bae94..e9fc896 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -12,6 +12,7 @@
 #include <linux/idr.h>
 #include <linux/bsg.h>
 #include <linux/slab.h>
+#include <linux/pm_runtime.h>
 
 #include <scsi/scsi.h>
 #include <scsi/scsi_ioctl.h>
@@ -306,12 +307,15 @@ static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
 static int bsg_open(struct inode *inode, struct file *file)
 {
 	struct bsg_device *bd;
+	struct bsg_class_device *bcd;
 
 	bd = bsg_get_device(inode, file);
 
 	if (IS_ERR(bd))
 		return PTR_ERR(bd);
 
+	bcd = &bd->queue->bsg_dev;
+	pm_runtime_get_sync(bcd->class_dev->parent);
 	file->private_data = bd;
 	return 0;
 }
@@ -319,8 +323,12 @@ static int bsg_open(struct inode *inode, struct file *file)
 static int bsg_release(struct inode *inode, struct file *file)
 {
 	struct bsg_device *bd = file->private_data;
+	struct bsg_class_device *bcd;
 
 	file->private_data = NULL;
+
+	bcd = &bd->queue->bsg_dev;
+	pm_runtime_put_sync(bcd->class_dev->parent);
 	return bsg_put_device(bd);
 }
 
-- 
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