linux-kernel - [PATCH 2/4] PCI/PTM: Enable PTM when restoring state

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Message-Id: <20220902145835.344302-3-helgaas@kernel.org>
Date:   Fri,  2 Sep 2022 09:58:33 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Rajvi Jingar <rajvi.jingar@...ux.intel.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>
Cc:     Koba Ko <koba.ko@...onical.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        "David E . Box" <david.e.box@...ux.intel.com>,
        Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        linux-pci@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH 2/4] PCI/PTM: Enable PTM when restoring state

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

The suspend path may disable PTM before saving config state, which means
the PCI_PTM_CTRL_ENABLE bit in the saved state may be cleared even though
we want PTM to be enabled when resuming.

If "dev->ptm_enabled" is set, it means PTM should be enabled, so make sure
PCI_PTM_CTRL_ENABLE is set when restoring the PTM state.

Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
---
 drivers/pci/pcie/ptm.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c
index b6a417247ce3..3115601a85ef 100644
--- a/drivers/pci/pcie/ptm.c
+++ b/drivers/pci/pcie/ptm.c
@@ -82,6 +82,14 @@ void pci_restore_ptm_state(struct pci_dev *dev)
 		return;
 
 	cap = (u16 *)&save_state->cap.data[0];
+
+	/*
+	 * The suspend path may disable PTM before saving config state.
+	 * Make sure PCI_PTM_CTRL_ENABLE is set if PTM should be enabled.
+	 */
+	if (dev->ptm_enabled)
+		*cap |= PCI_PTM_CTRL_ENABLE;
+
 	pci_write_config_word(dev, ptm + PCI_PTM_CTRL, *cap);
 }
 
-- 
2.25.1