[PATCH v2] PCI: rockchip: fix system hang up if activating CONFIG_DEBUG_SHIRQ

[Shawn Lin <shawn.lin@rock-chips.com>]

With CONFIG_DEBUG_SHIRQ enabled, the irq tear down routine
would still access the irq handler registed as a shard irq.
Per the comment within the function of __free_irq, it says
"It's a shared IRQ -- the driver ought to be prepared for
an IRQ event to happen even now it's being freed". However
when failing to probe the driver, it may disable the clock
for accessing the register and the following check for shared
irq state would call the irq handler which accesses the register
w/o the clk enabled. That will hang the system forever.

With adding some dump_stack we could see how that happened.

calling  rockchip_pcie_driver_init+0x0/0x28 @ 1
rockchip-pcie f8000000.pcie: no vpcie3v3 regulator found
rockchip-pcie f8000000.pcie: no vpcie1v8 regulator found
rockchip-pcie f8000000.pcie: no vpcie0v9 regulator found
rockchip-pcie f8000000.pcie: PCIe link training gen1 timeout!
CPU: 0 PID: 1 Comm: swapper/0 Not tainted
4.13.0-rc3-next-20170807-ARCH+ #189
Hardware name: Firefly-RK3399 Board (DT)
Call trace:
[<ffff000008089bf0>] dump_backtrace+0x0/0x250
[<ffff000008089eb0>] show_stack+0x20/0x28
[<ffff000008c3313c>] dump_stack+0x90/0xb0
[<ffff000008632ad4>] rockchip_pcie_read.isra.11+0x54/0x58
[<ffff0000086334fc>] rockchip_pcie_client_irq_handler+0x30/0x1a0
[<ffff00000813ce98>] __free_irq+0x1c8/0x2dc
[<ffff00000813d044>] free_irq+0x44/0x74
[<ffff0000081415fc>] devm_irq_release+0x24/0x2c
[<ffff00000877429c>] release_nodes+0x1d8/0x30c
[<ffff000008774838>] devres_release_all+0x3c/0x5c
[<ffff00000876f19c>] driver_probe_device+0x244/0x494
[<ffff00000876f50c>] __driver_attach+0x120/0x124
[<ffff00000876cb80>] bus_for_each_dev+0x6c/0xac
[<ffff00000876e984>] driver_attach+0x2c/0x34
[<ffff00000876e3a4>] bus_add_driver+0x244/0x2b0
[<ffff000008770264>] driver_register+0x70/0x110
[<ffff0000087718b4>] platform_driver_register+0x60/0x6c
[<ffff0000091eb108>] rockchip_pcie_driver_init+0x20/0x28
[<ffff000008083a2c>] do_one_initcall+0xc8/0x130
[<ffff0000091a0ea8>] kernel_init_freeable+0x1a0/0x238
[<ffff000008c461cc>] kernel_init+0x18/0x108
[<ffff0000080836c0>] ret_from_fork+0x10/0x50

In order to fix this, we remove all the clock-disabling from
the error handle path and driver's remove function. And replying
on the devm_add_action_or_reset to fire the clock-disabling at
the appropriate time.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>

---

Changes in v2:
- use devm_add_action_or_reset to fix this ordering suggested by
  Heiko and Jeffy. Thanks!

 drivers/pci/host/pcie-rockchip.c | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/drivers/pci/host/pcie-rockchip.c b/drivers/pci/host/pcie-rockchip.c
index 39aafe2..7713561 100644
--- a/drivers/pci/host/pcie-rockchip.c
+++ b/drivers/pci/host/pcie-rockchip.c
@@ -939,6 +939,16 @@ static int rockchip_pcie_get_phys(struct rockchip_pcie *rockchip)
 	return 0;
 }
 
+static void rockchip_pcie_disable_clocks(void *data)
+{
+	struct rockchip_pcie *rockchip = data;
+
+	clk_disable_unprepare(rockchip->clk_pcie_pm);
+	clk_disable_unprepare(rockchip->hclk_pcie);
+	clk_disable_unprepare(rockchip->aclk_perf_pcie);
+	clk_disable_unprepare(rockchip->aclk_pcie);
+}
+
 /**
  * rockchip_pcie_parse_dt - Parse Device Tree
  * @rockchip: PCIe port information
@@ -1071,6 +1081,9 @@ static int rockchip_pcie_parse_dt(struct rockchip_pcie *rockchip)
 		return -EINVAL;
 	}
 
+	devm_add_action_or_reset(dev,
+				 rockchip_pcie_disable_clocks, rockchip);
+
 	err = devm_request_irq(dev, irq, rockchip_pcie_subsys_irq_handler,
 			       IRQF_SHARED, "pcie-sys", rockchip);
 	if (err) {
@@ -1493,25 +1506,25 @@ static int rockchip_pcie_probe(struct platform_device *pdev)
 	err = clk_prepare_enable(rockchip->aclk_pcie);
 	if (err) {
 		dev_err(dev, "unable to enable aclk_pcie clock\n");
-		goto err_aclk_pcie;
+		return err;
 	}
 
 	err = clk_prepare_enable(rockchip->aclk_perf_pcie);
 	if (err) {
 		dev_err(dev, "unable to enable aclk_perf_pcie clock\n");
-		goto err_aclk_perf_pcie;
+		return err;
 	}
 
 	err = clk_prepare_enable(rockchip->hclk_pcie);
 	if (err) {
 		dev_err(dev, "unable to enable hclk_pcie clock\n");
-		goto err_hclk_pcie;
+		return err;
 	}
 
 	err = clk_prepare_enable(rockchip->clk_pcie_pm);
 	if (err) {
 		dev_err(dev, "unable to enable hclk_pcie clock\n");
-		goto err_pcie_pm;
+		return err;
 	}
 
 	err = rockchip_pcie_set_vpcie(rockchip);
@@ -1615,14 +1628,6 @@ static int rockchip_pcie_probe(struct platform_device *pdev)
 	if (!IS_ERR(rockchip->vpcie0v9))
 		regulator_disable(rockchip->vpcie0v9);
 err_set_vpcie:
-	clk_disable_unprepare(rockchip->clk_pcie_pm);
-err_pcie_pm:
-	clk_disable_unprepare(rockchip->hclk_pcie);
-err_hclk_pcie:
-	clk_disable_unprepare(rockchip->aclk_perf_pcie);
-err_aclk_perf_pcie:
-	clk_disable_unprepare(rockchip->aclk_pcie);
-err_aclk_pcie:
 	return err;
 }
 
@@ -1644,10 +1649,6 @@ static int rockchip_pcie_remove(struct platform_device *pdev)
 		phy_exit(rockchip->phys[i]);
 	}
 
-	clk_disable_unprepare(rockchip->clk_pcie_pm);
-	clk_disable_unprepare(rockchip->hclk_pcie);
-	clk_disable_unprepare(rockchip->aclk_perf_pcie);
-	clk_disable_unprepare(rockchip->aclk_pcie);
 
 	if (!IS_ERR(rockchip->vpcie12v))
 		regulator_disable(rockchip->vpcie12v);
-- 
1.9.1