An insertion following hotplug removal reads incorrect policy as
ASPM disabled even though ASPM was enabled during boot.

Adding a flag to the struct pci_dev and saving the power up policy
in the bridge to be reused during hotplug insertion. Bridge's enable
counter is used as a switch to determine when to use saved value.

Signed-off-by: Sinan Kaya <redacted>
---
drivers/pci/pcie/aspm.c | 21 +++++++++++++++++----
include/linux/pci.h     |  1 +
2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 17ac1dc..5cfcc6d 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c

@@ -338,8 +338,9 @@ static void pcie_aspm_check_latency(struct pci_dev *endpoint)

	}
}

-static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
+static void pcie_aspm_cap_init(struct pci_dev *pdev, int blacklist)
{
+	struct pcie_link_state *link = pdev->link_state;
	struct pci_dev *child, *parent = link->pdev;
	struct pci_bus *linkbus = parent->subordinate;
	struct aspm_register_info upreg, dwreg;

@@ -397,8 +398,20 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)

	link->latency_up.l1 = calc_l1_latency(upreg.latency_encoding_l1);
	link->latency_dw.l1 = calc_l1_latency(dwreg.latency_encoding_l1);

-	/* Save default state */
-	link->aspm_default = link->aspm_enabled;

+	/*
+	 * Save default state from FW when enabling ASPM for the first time
+	 * during boot by looking at the calculated link->aspm_enabled bits
+	 * above and enable_cnt will be zero.
+	 *
+	 * If this path is getting called for the second/third time
+	 * (enable_cnt will be non-zero). Assume that the current state of the
+	 * ASPM registers may not necessarily match what FW asked us to do as
+	 * in the case of hotplug insertion/removal.
+	 */
+	if (!atomic_read(&pdev->enable_cnt))
+		pdev->aspm_default = link->aspm_default = link->aspm_enabled;
+	else
+		link->aspm_default = pdev->aspm_default;

	/* Setup initial capable state. Will be updated later */
	link->aspm_capable = link->aspm_support;

@@ -599,7 +612,7 @@ void pcie_aspm_init_link_state(struct pci_dev *pdev)

	 * upstream links also because capable state of them can be
	 * update through pcie_aspm_cap_init().
	 */
-	pcie_aspm_cap_init(link, blacklist);
+	pcie_aspm_cap_init(pdev, blacklist);

	/* Setup initial Clock PM state */
	pcie_clkpm_cap_init(link, blacklist);

diff --git a/include/linux/pci.h b/include/linux/pci.h
index e2d1a12..521f88c 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h

@@ -321,6 +321,7 @@ struct pci_dev {

#ifdef CONFIG_PCIEASPM
	struct pcie_link_state	*link_state;	/* ASPM link state */
+	unsigned int	aspm_default;		/* ASPM policy set by BIOS */
#endif

	pci_channel_state_t error_state;	/* current connectivity state */
--
1.9.1

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