linux-kernel - [RESEND PATCH v3 2/2] PCI/PTM: fix to maintain pci_dev->ptm

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Date:   Tue, 30 Aug 2022 03:49:13 -0700
From:   Rajvi Jingar <rajvi.jingar@...ux.intel.com>
To:     rafael.j.wysocki@...el.com, bhelgaas@...gle.com
Cc:     rajvi.jingar@...ux.intel.com, david.e.box@...ux.intel.com,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: [RESEND PATCH v3 2/2] PCI/PTM: fix to maintain pci_dev->ptm_enabled

pci_dev->ptm_enabled needs to be maintained to reflect the current PTM
state of the device. In pci_ptm_disable(), clear ptm_enabled from
'struct pci_dev' on disabling PTM state for the device.
In pci_restore_ptm_state(), set dev->ptm_enabled based on the restored
PTM state of the device.

In pci_ptm_disable(), perform ptm_enabled check to avoid config space
access in case if PTM is already disabled for the device. ptm_enabled
won't be set for non-PCIe devices so pci_is_pcie(dev) check is not
needed anymore.

Signed-off-by: Rajvi Jingar <rajvi.jingar@...ux.intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 v1->v2:
   - add ptm_enabled check in pci_ptm_disable().
   - set the dev->ptm_enabled value in pci_restore_ptm_state().
 v2->v3:
   - remove pci_is_pcie(dev) check in pci_ptm_disable().
   - add Reviewed-by tag in commit message
---
 drivers/pci/pcie/ptm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c
index 368a254e3124..1ce241d4538f 100644
--- a/drivers/pci/pcie/ptm.c
+++ b/drivers/pci/pcie/ptm.c
@@ -34,7 +34,7 @@ void pci_disable_ptm(struct pci_dev *dev)
 	int ptm;
 	u16 ctrl;
 
-	if (!pci_is_pcie(dev))
+	if (!dev->ptm_enabled)
 		return;
 
 	ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
@@ -44,6 +44,7 @@ void pci_disable_ptm(struct pci_dev *dev)
 	pci_read_config_word(dev, ptm + PCI_PTM_CTRL, &ctrl);
 	ctrl &= ~(PCI_PTM_CTRL_ENABLE | PCI_PTM_CTRL_ROOT);
 	pci_write_config_word(dev, ptm + PCI_PTM_CTRL, ctrl);
+	dev->ptm_enabled = 0;
 }
 
 void pci_save_ptm_state(struct pci_dev *dev)
@@ -83,6 +84,7 @@ void pci_restore_ptm_state(struct pci_dev *dev)
 
 	cap = (u16 *)&save_state->cap.data[0];
 	pci_write_config_word(dev, ptm + PCI_PTM_CTRL, *cap);
+	dev->ptm_enabled = !!(*cap & PCI_PTM_CTRL_ENABLE);
 }
 
 void pci_ptm_init(struct pci_dev *dev)
-- 
2.25.1