linux-kernel - [PATCH v2 2/2] PCI/PTM: fix to maintain pci_dev->ptm

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Date:   Thu, 14 Jul 2022 16:16:09 -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: [PATCH v2 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.

Also, perform ptm_enabled check in pci_ptm_disable() to avoid config
space access in case if PTM is already disabled for the device.

Signed-off-by: Rajvi Jingar <rajvi.jingar@...ux.intel.com>
---
 v1->v2:
   - add ptm_enabled check in pci_ptm_disable().
   - set the dev->ptm_enabled value in pci_restore_ptm_state().
---
 drivers/pci/pcie/ptm.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c
index 368a254e3124..8dc7d2285a0d 100644
--- a/drivers/pci/pcie/ptm.c
+++ b/drivers/pci/pcie/ptm.c
@@ -34,6 +34,9 @@ void pci_disable_ptm(struct pci_dev *dev)
 	int ptm;
 	u16 ctrl;
 
+	if (!dev->ptm_enabled)
+		return;
+
 	if (!pci_is_pcie(dev))
 		return;
 
@@ -44,6 +47,7 @@ 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 +87,7 @@ 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