linux-kernel - [PATCH 1/2] Revert "PCI/ASPM: Save L1 PM Substates Capability for suspend/resume"

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Date:   Fri,  3 Feb 2023 16:48:19 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     linux-pci@...r.kernel.org
Cc:     Thomas Witt <kernel@...t.link>, Vidya Sagar <vidyas@...dia.com>,
        linux-kernel@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH 1/2] Revert "PCI/ASPM: Save L1 PM Substates Capability for suspend/resume"

From: Bjorn Helgaas <bhelgaas@...gle.com>

This reverts commit 4ff116d0d5fd8a025604b0802d93a2d5f4e465d1.

Thomas Witt reported that 5e85eba6f50d ("PCI/ASPM: Refactor L1 PM Substates
Control Register programming") broke suspend/resume.

4ff116d0d5fd ("PCI/ASPM: Save L1 PM Substates Capability for
suspend/resume") uses a function added by 5e85eba6f50d, so revert it first.

Note that reverting 4ff116d0d5fd means L1 Substates config will be lost on
suspend/resume.  As far as we know the box will use more power but will
still *work* correctly.

Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=216877
Reported-by: Thomas Witt <kernel@...t.link>
Tested-by: Thomas Witt <kernel@...t.link>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Vidya Sagar <vidyas@...dia.com>
---
 drivers/pci/pci.c       |  7 -------
 drivers/pci/pci.h       |  4 ----
 drivers/pci/pcie/aspm.c | 37 -------------------------------------
 3 files changed, 48 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index fba95486caaf..5641786bd020 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1665,7 +1665,6 @@ int pci_save_state(struct pci_dev *dev)
 		return i;
 
 	pci_save_ltr_state(dev);
-	pci_save_aspm_l1ss_state(dev);
 	pci_save_dpc_state(dev);
 	pci_save_aer_state(dev);
 	pci_save_ptm_state(dev);
@@ -1772,7 +1771,6 @@ void pci_restore_state(struct pci_dev *dev)
 	 * LTR itself (in the PCIe capability).
 	 */
 	pci_restore_ltr_state(dev);
-	pci_restore_aspm_l1ss_state(dev);
 
 	pci_restore_pcie_state(dev);
 	pci_restore_pasid_state(dev);
@@ -3465,11 +3463,6 @@ void pci_allocate_cap_save_buffers(struct pci_dev *dev)
 	if (error)
 		pci_err(dev, "unable to allocate suspend buffer for LTR\n");
 
-	error = pci_add_ext_cap_save_buffer(dev, PCI_EXT_CAP_ID_L1SS,
-					    2 * sizeof(u32));
-	if (error)
-		pci_err(dev, "unable to allocate suspend buffer for ASPM-L1SS\n");
-
 	pci_allocate_vc_save_buffers(dev);
 }
 
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 9ed3b5550043..9049d07d3aae 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -566,14 +566,10 @@ bool pcie_wait_for_link(struct pci_dev *pdev, bool active);
 void pcie_aspm_init_link_state(struct pci_dev *pdev);
 void pcie_aspm_exit_link_state(struct pci_dev *pdev);
 void pcie_aspm_powersave_config_link(struct pci_dev *pdev);
-void pci_save_aspm_l1ss_state(struct pci_dev *dev);
-void pci_restore_aspm_l1ss_state(struct pci_dev *dev);
 #else
 static inline void pcie_aspm_init_link_state(struct pci_dev *pdev) { }
 static inline void pcie_aspm_exit_link_state(struct pci_dev *pdev) { }
 static inline void pcie_aspm_powersave_config_link(struct pci_dev *pdev) { }
-static inline void pci_save_aspm_l1ss_state(struct pci_dev *dev) { }
-static inline void pci_restore_aspm_l1ss_state(struct pci_dev *dev) { }
 #endif
 
 #ifdef CONFIG_PCIE_ECRC
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 53a1fa306e1e..915cbd939dd9 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -757,43 +757,6 @@ static void pcie_config_aspm_l1ss(struct pcie_link_state *link, u32 state)
 				PCI_L1SS_CTL1_L1SS_MASK, val);
 }
 
-void pci_save_aspm_l1ss_state(struct pci_dev *dev)
-{
-	struct pci_cap_saved_state *save_state;
-	u16 l1ss = dev->l1ss;
-	u32 *cap;
-
-	if (!l1ss)
-		return;
-
-	save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_L1SS);
-	if (!save_state)
-		return;
-
-	cap = (u32 *)&save_state->cap.data[0];
-	pci_read_config_dword(dev, l1ss + PCI_L1SS_CTL2, cap++);
-	pci_read_config_dword(dev, l1ss + PCI_L1SS_CTL1, cap++);
-}
-
-void pci_restore_aspm_l1ss_state(struct pci_dev *dev)
-{
-	struct pci_cap_saved_state *save_state;
-	u32 *cap, ctl1, ctl2;
-	u16 l1ss = dev->l1ss;
-
-	if (!l1ss)
-		return;
-
-	save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_L1SS);
-	if (!save_state)
-		return;
-
-	cap = (u32 *)&save_state->cap.data[0];
-	ctl2 = *cap++;
-	ctl1 = *cap;
-	aspm_program_l1ss(dev, ctl1, ctl2);
-}
-
 static void pcie_config_aspm_dev(struct pci_dev *pdev, u32 val)
 {
 	pcie_capability_clear_and_set_word(pdev, PCI_EXP_LNKCTL,
-- 
2.25.1