[PATCH 06/15] PCI/ASPM: Save LTR state in the saved capability store

[David Matlack <dmatlack@google.com>]

Save and restore the LTR maximum latency registers through the per-device
saved capability store instead of a private pci_cap_saved_state buffer.

Reserve the DWORD by its configuration space offset during device setup,
and keep accessing the registers a DWORD at a time because some devices
only support DWORD access to them.

No functional change intended.

Assisted-by: LLM
Signed-off-by: David Matlack <dmatlack@google.com>
---
 drivers/pci/pci.c       | 12 ++++++++----
 drivers/pci/pcie/aspm.c | 19 +++----------------
 2 files changed, 11 insertions(+), 20 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 9e49806c6891..e53bca1cb50f 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3580,10 +3580,14 @@ void pci_allocate_cap_save_buffers(struct pci_dev *dev)
 			pci_err(dev, "unable to reserve PCI-X save state\n");
 	}
 
-	error = pci_add_ext_cap_save_buffer(dev, PCI_EXT_CAP_ID_LTR,
-					    2 * sizeof(u16));
-	if (error)
-		pci_err(dev, "unable to allocate suspend buffer for LTR\n");
+	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_LTR);
+	if (pos) {
+		unsigned int off = pos + PCI_LTR_MAX_SNOOP_LAT;
+
+		error = pci_reserve_saved_cap(dev, off, sizeof(u32));
+		if (error)
+			pci_err(dev, "unable to reserve LTR save state\n");
+	}
 
 	pci_allocate_vc_save_buffers(dev);
 }
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 02922b887ec6..16f22af98686 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -30,8 +30,6 @@
 void pci_save_ltr_state(struct pci_dev *dev)
 {
 	int ltr;
-	struct pci_cap_saved_state *save_state;
-	u32 *cap;
 
 	if (!pci_is_pcie(dev))
 		return;
@@ -40,31 +38,20 @@ void pci_save_ltr_state(struct pci_dev *dev)
 	if (!ltr)
 		return;
 
-	save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_LTR);
-	if (!save_state) {
-		pci_err(dev, "no suspend buffer for LTR; ASPM issues possible after resume\n");
-		return;
-	}
-
 	/* Some broken devices only support dword access to LTR */
-	cap = &save_state->cap.data[0];
-	pci_read_config_dword(dev, ltr + PCI_LTR_MAX_SNOOP_LAT, cap);
+	pci_save_cap_dword(dev, ltr + PCI_LTR_MAX_SNOOP_LAT);
 }
 
 void pci_restore_ltr_state(struct pci_dev *dev)
 {
-	struct pci_cap_saved_state *save_state;
 	int ltr;
-	u32 *cap;
 
-	save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_LTR);
 	ltr = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_LTR);
-	if (!save_state || !ltr)
+	if (!ltr)
 		return;
 
 	/* Some broken devices only support dword access to LTR */
-	cap = &save_state->cap.data[0];
-	pci_write_config_dword(dev, ltr + PCI_LTR_MAX_SNOOP_LAT, *cap);
+	pci_restore_cap_dword(dev, ltr + PCI_LTR_MAX_SNOOP_LAT);
 }
 
 void pci_configure_aspm_l1ss(struct pci_dev *pdev)
-- 
2.56.0.rc1.315.gc6ed9934b7-goog