PCI: tegra: Fix module remove sequence

Removing root port driver module will cause PERST# assert, which is
processed by execute pex_ep_event_pex_rst_assert() function in kthread
context. If endpoint driver module is removed immediately it will
free the interrupt, sometimes this happens before PERST# assert irq
is processed. To deinit controller execute pex_ep_event_pex_rst_assert()
function in rmmod. To avoid the race condition between the kthread and
rmmod, synchronize pex_ep_event_pex_rst_assert() function using mutex
lock.

bug 2422300

Change-Id: Id08c667c32aa240a150a2e8bb7b01367bec291f7
Signed-off-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1953518
Reviewed-by: Vidya Sagar <vidyas@nvidia.com>
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 14 insertions, 12 deletions

diff --git a/drivers/pci/ep/pcie-tegra-dw-ep.c b/drivers/pci/ep/pcie-tegra-dw-ep.c
index 68ff635a6..517ad45c9 100644
--- a/drivers/pci/ep/pcie-tegra-dw-ep.c
+++ b/drivers/pci/ep/pcie-tegra-dw-ep.c
@@ -282,8 +282,6 @@ enum ep_event {
         EP_PEX_RST_ASSERT,
         EP_PEX_HOT_RST_DONE,
         EP_PEX_BME_CHANGE,
-        EP_EVENT_EXIT,
-        EP_EVENT_INVALID,
 };
 
 enum margin_cmds {
@@ -319,6 +317,7 @@ struct tegra_pcie_dw_ep {
         int ep_state;
         struct phy **phy;
         struct task_struct *pcie_ep_task;
+        struct mutex disable_lock;
         wait_queue_head_t wq;
         DECLARE_KFIFO(event_fifo, u32, EVENT_QUEUE_LEN);
         u32 bar0_size;
@@ -579,8 +578,11 @@ static void pex_ep_event_pex_rst_assert(struct tegra_pcie_dw_ep *pcie)
         u32 val = 0;
         int ret = 0, count = 0;
 
-        if (pcie->ep_state == EP_STATE_DISABLED)
+        mutex_lock(&pcie->disable_lock);
+        if (pcie->ep_state == EP_STATE_DISABLED) {
+                mutex_unlock(&pcie->disable_lock);
                 return;
+        }
 
         /* disable LTSSM */
         val = readl(pcie->appl_base + APPL_CTRL);
@@ -621,6 +623,7 @@ static void pex_ep_event_pex_rst_assert(struct tegra_pcie_dw_ep *pcie)
         }
 
         pcie->ep_state = EP_STATE_DISABLED;
+        mutex_unlock(&pcie->disable_lock);
         dev_info(pcie->dev, "EP deinit done\n");
 }
 
@@ -947,13 +950,12 @@ static int pcie_ep_work_thread(void *p)
         struct tegra_pcie_dw_ep *pcie = (struct tegra_pcie_dw_ep *)p;
         u32 event = 0;
 
-        while (1) {
+        while (!kthread_should_stop()) {
                 wait_event_interruptible(pcie->wq,
-                                         !kfifo_is_empty(&pcie->event_fifo));
-
+                                         !kfifo_is_empty(&pcie->event_fifo) ||
+                                         kthread_should_stop());
                 if (kthread_should_stop())
                         break;
-
                 if (!kfifo_get(&pcie->event_fifo, &event)) {
                         dev_warn(pcie->dev, "empty kfifo\n");
                         continue;
@@ -992,10 +994,8 @@ static void tegra_pcie_disable_phy(struct tegra_pcie_dw_ep *pcie)
 {
         int phy_count = pcie->phy_count;
 
-        while (phy_count--) {
-                phy_power_off(pcie->phy[phy_count]);
+        while (phy_count--)
                 phy_exit(pcie->phy[phy_count]);
-        }
 }
 
 static int tegra_pcie_init_phy(struct tegra_pcie_dw_ep *pcie)
@@ -1424,6 +1424,7 @@ static int tegra_pcie_dw_ep_probe(struct platform_device *pdev)
 
         pcie->dev = &pdev->dev;
         pcie->ep_state = EP_STATE_DISABLED;
+        mutex_init(&pcie->disable_lock);
 
         ret = of_property_read_u32(np, "num-lanes", &pcie->num_lanes);
         if (ret < 0) {
@@ -1777,9 +1778,10 @@ static int tegra_pcie_dw_ep_remove(struct platform_device *pdev)
 
         debugfs_remove_recursive(pcie->debugfs);
 
-        if (!kfifo_put(&pcie->event_fifo, EP_EVENT_EXIT))
-                dev_err(pcie->dev, "EVENT: fifo is full\n");
         kthread_stop(pcie->pcie_ep_task);
+        pex_ep_event_pex_rst_assert(pcie);
+
+        pm_runtime_disable(pcie->dev);
 
         tegra_bwmgr_unregister(pcie->emc_bw);