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Subject[PATCH 4.14 031/193] PCI/ASPM: Use correct capability pointer to program LTR_L1.2_THRESHOLD
4.14-stable review patch.  If anyone has any objections, please let me know.


From: Bjorn Helgaas <>

commit c00054f540bf81e592e1fee709b0bdbf20f478b5 upstream.

Previously we programmed the LTR_L1.2_THRESHOLD in the parent (upstream)
device using the capability pointer of the *child* (downstream) device,
which corrupted some random word of the parent's config space.

Use the parent's L1 SS capability pointer to program its

Fixes: aeda9adebab8 ("PCI/ASPM: Configure L1 substate settings")
Signed-off-by: Bjorn Helgaas <>
Reviewed-by: Vidya Sagar <>
CC: Rajat Jain <>
Signed-off-by: Greg Kroah-Hartman <>

drivers/pci/pcie/aspm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -658,7 +658,7 @@ static void pcie_config_aspm_l1ss(struct
0xFF00, link->l1ss.ctl1);

/* Program LTR L1.2 threshold in both ports */
- pci_clear_and_set_dword(parent, dw_cap_ptr + PCI_L1SS_CTL1,
+ pci_clear_and_set_dword(parent, up_cap_ptr + PCI_L1SS_CTL1,
0xE3FF0000, link->l1ss.ctl1);
pci_clear_and_set_dword(child, dw_cap_ptr + PCI_L1SS_CTL1,
0xE3FF0000, link->l1ss.ctl1);

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