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From:   Zhiqiang Hou <Zhiqiang.Hou@nxp.com>
To:     linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org
Cc:     robh@kernel.org, lorenzo.pieralisi@arm.com, bhelgaas@google.com,
        gustavo.pimentel@synopsys.com, Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Subject: [PATCH] PCI: dwc: Added link up check in map_bus of dw_child_pcie_ops
Date:   Wed, 16 Sep 2020 13:41:30 +0800
Message-Id: <20200916054130.8685-1-Zhiqiang.Hou@nxp.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>

On NXP Layerscape platforms, it results in SError in the
enumeration of the PCIe controller, which is not connecting
with an Endpoint device. And it doesn't make sense to
enumerate the Endpoints when the PCIe link is down. So this
patch added the link up check to avoid to fire configuration
transactions on link down bus.

[    0.807773] SError Interrupt on CPU2, code 0xbf000002 -- SError
[    0.807775] CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.9.0-rc5-next-20200914-00001-gf965d3ec86fa #67
[    0.807776] Hardware name: LS1046A RDB Board (DT)
[    0.807777] pstate: 20000085 (nzCv daIf -PAN -UAO BTYPE=--)
[    0.807778] pc : pci_generic_config_read+0x3c/0xe0
[    0.807778] lr : pci_generic_config_read+0x24/0xe0
[    0.807779] sp : ffff80001003b7b0
[    0.807780] x29: ffff80001003b7b0 x28: ffff80001003ba74
[    0.807782] x27: ffff000971d96800 x26: ffff00096e77e0a8
[    0.807784] x25: ffff80001003b874 x24: ffff80001003b924
[    0.807786] x23: 0000000000000004 x22: 0000000000000000
[    0.807788] x21: 0000000000000000 x20: ffff80001003b874
[    0.807790] x19: 0000000000000004 x18: ffffffffffffffff
[    0.807791] x17: 00000000000000c0 x16: fffffe0025981840
[    0.807793] x15: ffffb94c75b69948 x14: 62203a383634203a
[    0.807795] x13: 666e6f635f726568 x12: 202c31203d207265
[    0.807797] x11: 626d756e3e2d7375 x10: 656877202c307830
[    0.807799] x9 : 203d206e66766564 x8 : 0000000000000908
[    0.807801] x7 : 0000000000000908 x6 : ffff800010900000
[    0.807802] x5 : ffff00096e77e080 x4 : 0000000000000000
[    0.807804] x3 : 0000000000000003 x2 : 84fa3440ff7e7000
[    0.807806] x1 : 0000000000000000 x0 : ffff800010034000
[    0.807808] Kernel panic - not syncing: Asynchronous SError Interrupt
[    0.807809] CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.9.0-rc5-next-20200914-00001-gf965d3ec86fa #67
[    0.807810] Hardware name: LS1046A RDB Board (DT)
[    0.807811] Call trace:
[    0.807812]  dump_backtrace+0x0/0x1c0
[    0.807813]  show_stack+0x18/0x28
[    0.807814]  dump_stack+0xd8/0x134
[    0.807814]  panic+0x180/0x398
[    0.807815]  add_taint+0x0/0xb0
[    0.807816]  arm64_serror_panic+0x78/0x88
[    0.807817]  do_serror+0x68/0x180
[    0.807818]  el1_error+0x84/0x100
[    0.807818]  pci_generic_config_read+0x3c/0xe0
[    0.807819]  dw_pcie_rd_other_conf+0x78/0x110
[    0.807820]  pci_bus_read_config_dword+0x88/0xe8
[    0.807821]  pci_bus_generic_read_dev_vendor_id+0x30/0x1b0
[    0.807822]  pci_bus_read_dev_vendor_id+0x4c/0x78
[    0.807823]  pci_scan_single_device+0x80/0x100
[    0.807824]  pci_scan_slot+0x38/0x130
[    0.807825]  pci_scan_child_bus_extend+0x54/0x2a0
[    0.807826]  pci_scan_child_bus+0x14/0x20
[    0.807827]  pci_scan_bridge_extend+0x230/0x570
[    0.807828]  pci_scan_child_bus_extend+0x134/0x2a0
[    0.807829]  pci_scan_root_bus_bridge+0x64/0xf0
[    0.807829]  pci_host_probe+0x18/0xc8
[    0.807830]  dw_pcie_host_init+0x220/0x378
[    0.807831]  ls_pcie_probe+0x104/0x140
[    0.807832]  platform_drv_probe+0x54/0xa8
[    0.807833]  really_probe+0x118/0x3e0
[    0.807834]  driver_probe_device+0x5c/0xc0
[    0.807835]  device_driver_attach+0x74/0x80
[    0.807835]  __driver_attach+0x8c/0xd8
[    0.807836]  bus_for_each_dev+0x7c/0xd8
[    0.807837]  driver_attach+0x24/0x30
[    0.807838]  bus_add_driver+0x154/0x200
[    0.807839]  driver_register+0x64/0x120
[    0.807839]  __platform_driver_probe+0x7c/0x148
[    0.807840]  ls_pcie_driver_init+0x24/0x30
[    0.807841]  do_one_initcall+0x60/0x1d8
[    0.807842]  kernel_init_freeable+0x1f4/0x24c
[    0.807843]  kernel_init+0x14/0x118
[    0.807843]  ret_from_fork+0x10/0x34
[    0.807854] SMP: stopping secondary CPUs
[    0.807855] Kernel Offset: 0x394c64080000 from 0xffff800010000000
[    0.807856] PHYS_OFFSET: 0xffff8bfd40000000
[    0.807856] CPU features: 0x0240022,21806000
[    0.807857] Memory Limit: none

Fixes: c2b0c098fbd1 ("PCI: dwc: Use generic config accessors")
Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
---
 drivers/pci/controller/dwc/pcie-designware-host.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index c01c9d2fb3f9..e82b518430c5 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -442,6 +442,9 @@ static void __iomem *dw_pcie_other_conf_map_bus(struct pci_bus *bus,
 	struct pcie_port *pp = bus->sysdata;
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
 
+	if (!dw_pcie_link_up(pci))
+		return NULL;
+
 	busdev = PCIE_ATU_BUS(bus->number) | PCIE_ATU_DEV(PCI_SLOT(devfn)) |
 		 PCIE_ATU_FUNC(PCI_FUNC(devfn));
 
-- 
2.17.1