[PATCH 20/24] thunderbolt: Do not touch the hardware if the NHI is gone on resume

[Mika Westerberg <mika.westerberg@linux.intel.com>]

On PCs the NHI host controller is only present when there is a device
connected. When the last device is disconnected the host controller will
dissappear shortly (within 10s). Now if that happens when we are
suspended we should not try to touch the hardware anymore, so add a flag
for this and check it before we re-enable rings.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com>
Reviewed-by: Michael Jamet <michael.jamet@intel.com>
---
 drivers/thunderbolt/nhi.c | 14 ++++++++++++++
 drivers/thunderbolt/nhi.h |  3 +++
 2 files changed, 17 insertions(+)

diff --git a/drivers/thunderbolt/nhi.c b/drivers/thunderbolt/nhi.c
index db9dca11e5db..c11e4009325b 100644
--- a/drivers/thunderbolt/nhi.c
+++ b/drivers/thunderbolt/nhi.c
@@ -404,6 +404,8 @@ void ring_start(struct tb_ring *ring)
 {
 	mutex_lock(&ring->nhi->lock);
 	mutex_lock(&ring->lock);
+	if (ring->nhi->going_away)
+		goto err;
 	if (ring->running) {
 		dev_WARN(&ring->nhi->pdev->dev, "ring already started\n");
 		goto err;
@@ -451,6 +453,8 @@ void ring_stop(struct tb_ring *ring)
 	mutex_lock(&ring->lock);
 	dev_info(&ring->nhi->pdev->dev, "stopping %s %d\n",
 		 RING_TYPE(ring), ring->hop);
+	if (ring->nhi->going_away)
+		goto err;
 	if (!ring->running) {
 		dev_WARN(&ring->nhi->pdev->dev, "%s %d already stopped\n",
 			 RING_TYPE(ring), ring->hop);
@@ -655,6 +659,16 @@ static int nhi_resume_noirq(struct device *dev)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct tb *tb = pci_get_drvdata(pdev);
+	u32 vid;
+
+	/*
+	 * Check that the device is still there. It may be that the user
+	 * unplugged last device which causes the host controller to go
+	 * away on PCs.
+	 */
+	pci_read_config_dword(pdev, PCI_VENDOR_ID, &vid);
+	if (vid == ~0)
+		tb->nhi->going_away = true;
 
 	return tb_domain_resume_noirq(tb);
 }
diff --git a/drivers/thunderbolt/nhi.h b/drivers/thunderbolt/nhi.h
index 730ece3a8a5a..243f5fcfa367 100644
--- a/drivers/thunderbolt/nhi.h
+++ b/drivers/thunderbolt/nhi.h
@@ -20,6 +20,8 @@
  * @tx_rings: All Tx rings available on this host controller
  * @rx_rings: All Rx rings available on this host controller
  * @msix_ida: Used to allocate MSI-X vectors for rings
+ * @going_away: The host controller device is about to disappear so when
+ *		this flag is set, avoid touching the hardware anymore.
  * @interrupt_work: Work scheduled to handle ring interrupt when no
  *		    MSI-X is used.
  * @hop_count: Number of rings (end point hops) supported by NHI.
@@ -31,6 +33,7 @@ struct tb_nhi {
 	struct tb_ring **tx_rings;
 	struct tb_ring **rx_rings;
 	struct ida msix_ida;
+	bool going_away;
 	struct work_struct interrupt_work;
 	u32 hop_count;
 };
-- 
2.11.0