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From:   Takashi Iwai <tiwai@suse.de>
To:     dri-devel@lists.freedesktop.org
Cc:     Dave Airlie <airlied@redhat.com>, Sean Paul <sean@poorly.run>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        linux-kernel@vger.kernel.org
Subject: [PATCH 2/4] drm/udl: Sync pending URBs at suspend / disconnect
Date:   Thu,  4 Aug 2022 09:58:24 +0200
Message-Id: <20220804075826.27036-3-tiwai@suse.de>
In-Reply-To: <20220804075826.27036-1-tiwai@suse.de>
References: <20220804075826.27036-1-tiwai@suse.de>
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We need to wait for finishing to process the all URBs after disabling
the pipe; otherwise pending URBs may stray at suspend/resume, leading
to a possible memory corruption in a worst case.

Tested-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 drivers/gpu/drm/udl/udl_drv.h     |  1 +
 drivers/gpu/drm/udl/udl_main.c    | 17 +++++++++++++++++
 drivers/gpu/drm/udl/udl_modeset.c |  2 ++
 3 files changed, 20 insertions(+)

diff --git a/drivers/gpu/drm/udl/udl_drv.h b/drivers/gpu/drm/udl/udl_drv.h
index e008686ec738..f01e50c5b7b7 100644
--- a/drivers/gpu/drm/udl/udl_drv.h
+++ b/drivers/gpu/drm/udl/udl_drv.h
@@ -83,6 +83,7 @@ static inline struct urb *udl_get_urb(struct drm_device *dev)
 }
 
 int udl_submit_urb(struct drm_device *dev, struct urb *urb, size_t len);
+int udl_sync_pending_urbs(struct drm_device *dev);
 void udl_urb_completion(struct urb *urb);
 
 int udl_init(struct udl_device *udl);
diff --git a/drivers/gpu/drm/udl/udl_main.c b/drivers/gpu/drm/udl/udl_main.c
index 67fd41e59b80..93615648414b 100644
--- a/drivers/gpu/drm/udl/udl_main.c
+++ b/drivers/gpu/drm/udl/udl_main.c
@@ -270,6 +270,23 @@ int udl_submit_urb(struct drm_device *dev, struct urb *urb, size_t len)
 	return ret;
 }
 
+/* wait until all pending URBs have been processed */
+int udl_sync_pending_urbs(struct drm_device *dev)
+{
+	struct udl_device *udl = to_udl(dev);
+	int ret = 0;
+
+	spin_lock_irq(&udl->urbs.lock);
+	/* 2 seconds as a sane timeout */
+	if (!wait_event_lock_irq_timeout(udl->urbs.sleep,
+					 udl->urbs.available == udl->urbs.count,
+					 udl->urbs.lock,
+					 msecs_to_jiffies(2000)))
+		ret = -ETIMEDOUT;
+	spin_unlock_irq(&udl->urbs.lock);
+	return ret;
+}
+
 int udl_init(struct udl_device *udl)
 {
 	struct drm_device *dev = &udl->drm;
diff --git a/drivers/gpu/drm/udl/udl_modeset.c b/drivers/gpu/drm/udl/udl_modeset.c
index e67c40a48fb4..50025606b6ad 100644
--- a/drivers/gpu/drm/udl/udl_modeset.c
+++ b/drivers/gpu/drm/udl/udl_modeset.c
@@ -408,6 +408,8 @@ udl_simple_display_pipe_disable(struct drm_simple_display_pipe *pipe)
 	buf = udl_dummy_render(buf);
 
 	udl_submit_urb(dev, urb, buf - (char *)urb->transfer_buffer);
+
+	udl_sync_pending_urbs(dev);
 }
 
 static void
-- 
2.35.3