When the operating system is booted with the default ASPM policy
(POLICY_DEFAULT), the current code is determining the ASPM policy
set up by the BIOS by querying the enable/disable states from ASPM
registers.
In the case of hotplug removal, the ASPM registers get cleared by
calling the pcie_aspm_exit_link_state() function.
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 <okaya@xxxxxxxxxxxxxx>
---
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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