[PATCH] PCI: Add CRS timeout for pci_device_is_present()

From: Vidya Sagar <vidyas@nvidia.com>
To: <bhelgaas@google.com>, <lorenzo.pieralisi@arm.com>,
	<treding@nvidia.com>, <jonathanh@nvidia.com>
Cc: <linux-tegra@vger.kernel.org>, <linux-pci@vger.kernel.org>,
	<kthota@nvidia.com>, <mmaddireddy@nvidia.com>,
	<vidyas@nvidia.com>, <sagar.tv@gmail.com>
Subject: [PATCH] PCI: Add CRS timeout for pci_device_is_present()
Date: Sat, 5 Oct 2019 23:51:29 +0530	[thread overview]
Message-ID: <20191005182129.32538-1-vidyas@nvidia.com> (raw)

Adds a 60 seconds timeout to consider CRS (Configuration request Retry
Status) from a downstream device when Vendor ID read is attempted by
an upstream device. This helps to work with devices that return CRS
during system resume. This also makes pci_device_is_present() consistent
with the probe path where 60 seconds timeout is already being used.

Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
---
 drivers/pci/pci.c   | 3 ++-
 drivers/pci/pci.h   | 2 ++
 drivers/pci/probe.c | 2 +-
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 95dc78ebdded..3ab9f6d3c8a6 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5905,7 +5905,8 @@ bool pci_device_is_present(struct pci_dev *pdev)
 
 	if (pci_dev_is_disconnected(pdev))
 		return false;
-	return pci_bus_read_dev_vendor_id(pdev->bus, pdev->devfn, &v, 0);
+	return pci_bus_read_dev_vendor_id(pdev->bus, pdev->devfn, &v,
+					  PCI_CRS_TIMEOUT);
 }
 EXPORT_SYMBOL_GPL(pci_device_is_present);
 
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 3f6947ee3324..aa25c5fdc6a5 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -4,6 +4,8 @@
 
 #include <linux/pci.h>
 
+#define PCI_CRS_TIMEOUT		(60 * 1000)	/* 60 sec*/
+
 #define PCI_FIND_CAP_TTL	48
 
 #define PCI_VSEC_ID_INTEL_TBT	0x1234	/* Thunderbolt */
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 7c5d68b807ef..6e44a03283c8 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2258,7 +2258,7 @@ static struct pci_dev *pci_scan_device(struct pci_bus *bus, int devfn)
 	struct pci_dev *dev;
 	u32 l;
 
-	if (!pci_bus_read_dev_vendor_id(bus, devfn, &l, 60*1000))
+	if (!pci_bus_read_dev_vendor_id(bus, devfn, &l, PCI_CRS_TIMEOUT))
 		return NULL;
 
 	dev = pci_alloc_dev(bus);
-- 
2.17.1

