Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Received-SPF: Pass (protection.outlook.com: domain of nvidia.com designates
 12.22.5.234 as permitted sender) receiver=protection.outlook.com;
 client-ip=12.22.5.234; helo=mail.nvidia.com; pr=C
From:   Vidya Sagar <vidyas@nvidia.com>
To:     <bhelgaas@google.com>, <lorenzo.pieralisi@arm.com>,
        <refactormyself@gmail.com>, <kw@linux.com>, <rajatja@google.com>,
        <kenny@panix.com>, <kai.heng.feng@canonical.com>,
        <treding@nvidia.com>, <jonathanh@nvidia.com>, <abhsahu@nvidia.com>,
        <sagupta@nvidia.com>
CC:     <benchuanggli@gmail.com>, <linux-pci@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <kthota@nvidia.com>,
        <mmaddireddy@nvidia.com>, <vidyas@nvidia.com>, <sagar.tv@gmail.com>
Subject: [PATCH V3] PCI/ASPM: Save/restore L1SS Capability for suspend/resume
Date:   Fri, 26 Aug 2022 18:25:26 +0530
Message-ID: <20220826125526.28859-1-vidyas@nvidia.com>
MIME-Version: 1.0
Content-Type: text/plain
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 26 Aug 2022 12:55:34.9336
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: 019dc06c-1db8-4fe5-0f55-08da87624466
X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[12.22.5.234];Helo=[mail.nvidia.com]
X-MS-Exchange-CrossTenant-AuthSource: CO1NAM11FT065.eop-nam11.prod.protection.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Anonymous
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB6491
X-Spam-Status: No, score=-1.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
        DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FORGED_SPF_HELO,
        RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_NONE,
        T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Previously ASPM L1 Substates control registers (CTL1 and CTL2) weren't
saved and restored during suspend/resume leading to L1 Substates
configuration being lost post-resume.

Save the L1 Substates control registers so that the configuration is
retained post-resume.

Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
---
V3:
* Disabled L1.2 enable fields while restoring Control-1 register

Hi Kai-Heng,
Could you please try this patch on your setup?

Thanks & Regards,
Vidya Sagar

 drivers/pci/pci.c       |  7 ++++++
 drivers/pci/pci.h       |  4 ++++
 drivers/pci/pcie/aspm.c | 50 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 61 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 95bc329e74c0..68a49fbaabde 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1663,6 +1663,7 @@ 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);
@@ -1769,6 +1770,7 @@ 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);
@@ -3485,6 +3487,11 @@ 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 785f31086313..365a844ec430 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -561,10 +561,14 @@ 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 a8aec190986c..ee1f651bb1af 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -726,6 +726,56 @@ 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)
+{
+	int aspm_l1ss;
+	struct pci_cap_saved_state *save_state;
+	u32 *cap;
+
+	if (!pci_is_pcie(dev))
+		return;
+
+	aspm_l1ss = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_L1SS);
+	if (!aspm_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, aspm_l1ss + PCI_L1SS_CTL2, cap++);
+	pci_read_config_dword(dev, aspm_l1ss + PCI_L1SS_CTL1, cap++);
+}
+
+void pci_restore_aspm_l1ss_state(struct pci_dev *dev)
+{
+	int aspm_l1ss;
+	struct pci_cap_saved_state *save_state;
+	u32 *cap, l1_2_enable;
+
+	if (!pci_is_pcie(dev))
+		return;
+
+	aspm_l1ss = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_L1SS);
+	if (!aspm_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_write_config_dword(dev, aspm_l1ss + PCI_L1SS_CTL2, *cap++);
+	/* Disable L1.2 while updating.  See PCIe r5.0, sec 5.5.4, 7.8.3.3 */
+	l1_2_enable = *cap & PCI_L1SS_CTL1_L1_2_MASK;
+	pci_write_config_dword(dev, aspm_l1ss + PCI_L1SS_CTL1,
+			       (*cap & ~PCI_L1SS_CTL1_L1_2_MASK));
+	if (l1_2_enable)
+		pci_clear_and_set_dword(dev, aspm_l1ss + PCI_L1SS_CTL1, 0,
+					l1_2_enable);
+}
+
 static void pcie_config_aspm_dev(struct pci_dev *pdev, u32 val)
 {
 	pcie_capability_clear_and_set_word(pdev, PCI_EXP_LNKCTL,
-- 
2.17.1