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Message-Id: <20210128122311.1.I42c1001f8b0eaac973a99e1e5c2170788ee36c9c@changeid>
Date: Thu, 28 Jan 2021 12:27:54 +0000
From: Victor Ding <victording@...gle.com>
To: Bjorn Helgaas <helgaas@...nel.org>,
Ulf Hansson <ulf.hansson@...aro.org>,
Adrian Hunter <adrian.hunter@...el.com>
Cc: linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-pci@...r.kernel.org,
Ben Chuang <ben.chuang@...esyslogic.com.tw>,
Victor Ding <victording@...gle.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Kai-Heng Feng <kai.heng.feng@...onical.com>,
"Saheed O. Bolarinwa" <refactormyself@...il.com>,
Vidya Sagar <vidyas@...dia.com>,
Xiongfeng Wang <wangxiongfeng2@...wei.com>,
Yicong Yang <yangyicong@...ilicon.com>
Subject: [PATCH] PCI/ASPM: Disable ASPM when save/restore PCI state
Certain PCIe devices (e.g. GL9750) have high penalties (e.g. high Port
T_POWER_ON) when exiting L1 but enter L1 aggressively. As a result,
such devices enter and exit L1 frequently during pci_save_state and
pci_restore_state; eventually causing poor suspend/resume performance.
Based on the observation that PCI accesses dominance pci_save_state/
pci_restore_state plus these accesses are fairly close to each other, the
actual time the device could stay in low power states is negligible.
Therefore, the little power-saving benefit from ASPM during suspend/resume
does not overweight the performance degradation caused by high L1 exit
penalties.
Therefore, this patch proposes to disable ASPM during a suspend/resume
process.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=211187
Signed-off-by: Victor Ding <victording@...gle.com>
---
drivers/pci/pci.c | 18 +++++++++++++++---
drivers/pci/pci.h | 6 ++++++
drivers/pci/pcie/aspm.c | 26 ++++++++++++++++++++++++++
include/linux/pci.h | 1 +
4 files changed, 48 insertions(+), 3 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 32011b7b4c04..a925a7075063 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1542,6 +1542,10 @@ static void pci_restore_ltr_state(struct pci_dev *dev)
int pci_save_state(struct pci_dev *dev)
{
int i;
+
+ pcie_save_aspm_control(dev);
+ pcie_disable_aspm(dev);
+
/* XXX: 100% dword access ok here? */
for (i = 0; i < 16; i++) {
pci_read_config_dword(dev, i * 4, &dev->saved_config_space[i]);
@@ -1552,18 +1556,22 @@ int pci_save_state(struct pci_dev *dev)
i = pci_save_pcie_state(dev);
if (i != 0)
- return i;
+ goto Exit;
i = pci_save_pcix_state(dev);
if (i != 0)
- return i;
+ goto Exit;
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);
- return pci_save_vc_state(dev);
+ i = pci_save_vc_state(dev);
+
+Exit:
+ pcie_restore_aspm_control(dev);
+ return i;
}
EXPORT_SYMBOL(pci_save_state);
@@ -1661,6 +1669,8 @@ void pci_restore_state(struct pci_dev *dev)
if (!dev->state_saved)
return;
+ pcie_disable_aspm(dev);
+
/*
* Restore max latencies (in the LTR capability) before enabling
* LTR itself (in the PCIe capability).
@@ -1689,6 +1699,8 @@ void pci_restore_state(struct pci_dev *dev)
pci_enable_acs(dev);
pci_restore_iov_state(dev);
+ pcie_restore_aspm_control(dev);
+
dev->state_saved = false;
}
EXPORT_SYMBOL(pci_restore_state);
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index a81459159f6d..e074a0cbe73c 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -584,6 +584,9 @@ void pcie_aspm_pm_state_change(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);
+void pcie_save_aspm_control(struct pci_dev *dev);
+void pcie_restore_aspm_control(struct pci_dev *dev);
+void pcie_disable_aspm(struct pci_dev *pdev);
#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) { }
@@ -591,6 +594,9 @@ static inline void pcie_aspm_pm_state_change(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) { }
+static inline void pcie_save_aspm_control(struct pci_dev *dev) { }
+static inline void pcie_restore_aspm_control(struct pci_dev *dev) { }
+static inline void pcie_disable_aspm(struct pci_dev *pdev) { }
#endif
#ifdef CONFIG_PCIE_ECRC
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index a08e7d6dc248..519b9f1b067a 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -105,6 +105,12 @@ static const char *policy_str[] = {
#define LINK_RETRAIN_TIMEOUT HZ
+void pcie_disable_aspm(struct pci_dev *pdev)
+{
+ pcie_capability_clear_and_set_word(pdev, PCI_EXP_LNKCTL,
+ PCI_EXP_LNKCTL_ASPMC, 0);
+}
+
static int policy_to_aspm_state(struct pcie_link_state *link)
{
switch (aspm_policy) {
@@ -680,6 +686,26 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
}
}
+void pcie_save_aspm_control(struct pci_dev *dev)
+{
+ u16 lnkctl;
+
+ if (!pci_is_pcie(dev))
+ return;
+
+ pci_read_config_word(dev, PCI_EXP_LNKCTL, &lnkctl);
+ dev->saved_aspm_ctl = lnkctl & PCI_EXP_LNKCTL_ASPMC;
+}
+
+void pcie_restore_aspm_control(struct pci_dev *dev)
+{
+ if (!pci_is_pcie(dev))
+ return;
+
+ pcie_capability_clear_and_set_word(dev, PCI_EXP_LNKCTL,
+ PCI_EXP_LNKCTL_ASPMC, dev->saved_aspm_ctl);
+}
+
/* Configure the ASPM L1 substates */
static void pcie_config_aspm_l1ss(struct pcie_link_state *link, u32 state)
{
diff --git a/include/linux/pci.h b/include/linux/pci.h
index b32126d26997..a21bfd6e3f89 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -387,6 +387,7 @@ struct pci_dev {
unsigned int ltr_path:1; /* Latency Tolerance Reporting
supported from root to here */
u16 l1ss; /* L1SS Capability pointer */
+ u16 saved_aspm_ctl; /* ASPM Control saved at suspend time */
#endif
unsigned int eetlp_prefix_path:1; /* End-to-End TLP Prefix */
--
2.30.0.280.ga3ce27912f-goog
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