From: Bjorn Helgaas <helgaas@kernel.org>
To: "Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>
Cc: linux-pci@vger.kernel.org,
"Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
"Rob Herring" <robh@kernel.org>,
"Krzysztof Wilczyński" <kw@linux.com>,
"Lukas Wunner" <lukas@wunner.de>,
"Rafael J . Wysocki" <rafael@kernel.org>,
"Heiner Kallweit" <hkallweit1@gmail.com>,
"Emmanuel Grumbach" <emmanuel.grumbach@intel.com>,
linux-kernel@vger.kernel.org,
"Bjorn Helgaas" <bhelgaas@google.com>,
ath10k@lists.infradead.org, ath11k@lists.infradead.org,
ath12k@lists.infradead.org, intel-wired-lan@lists.osuosl.org,
linux-arm-kernel@lists.infradead.org,
linux-bluetooth@vger.kernel.org,
linux-mediatek@lists.infradead.org, linux-rdma@vger.kernel.org,
linux-wireless@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH v2 05/13] PCI/ASPM: Add pci_enable_link_state()
Date: Wed, 11 Oct 2023 16:53:27 -0500 [thread overview]
Message-ID: <20231011215327.GA1043654@bhelgaas> (raw)
In-Reply-To: <20230918131103.24119-6-ilpo.jarvinen@linux.intel.com>
On Mon, Sep 18, 2023 at 04:10:55PM +0300, Ilpo Järvinen wrote:
> pci_disable_link_state() lacks a symmetric pair. Some drivers want to
> disable ASPM during certain phases of their operation but then
> re-enable it later on. If pci_disable_link_state() is made for the
> device, there is currently no way to re-enable the states that were
> disabled.
pci_disable_link_state() gives drivers a way to disable specified ASPM
states using a bitmask (PCIE_LINK_STATE_L0S, PCIE_LINK_STATE_L1,
PCIE_LINK_STATE_L1_1, etc), but IIUC the driver can't tell exactly
what changed and can't directly restore the original state, e.g.,
- PCIE_LINK_STATE_L1 enabled initially
- driver calls pci_disable_link_state(PCIE_LINK_STATE_L0S)
- driver calls pci_enable_link_state(PCIE_LINK_STATE_L0S)
- PCIE_LINK_STATE_L0S and PCIE_LINK_STATE_L1 are enabled now
Now PCIE_LINK_STATE_L0S is enabled even though it was not initially
enabled. Maybe that's what we want; I dunno.
pci_disable_link_state() currently returns success/failure, but only
r8169 and mt76 even check, and only rtl_init_one() (r8169) has a
non-trivial reason, so it's conceivable that it could return a bitmask
instead.
> Add pci_enable_link_state() to remove ASPM states from the state
> disable mask.
>
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> ---
> drivers/pci/pcie/aspm.c | 42 +++++++++++++++++++++++++++++++++++++++++
> include/linux/pci.h | 2 ++
> 2 files changed, 44 insertions(+)
>
> diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
> index 91dc95aca90f..f45d18d47c20 100644
> --- a/drivers/pci/pcie/aspm.c
> +++ b/drivers/pci/pcie/aspm.c
> @@ -1117,6 +1117,48 @@ int pci_disable_link_state(struct pci_dev *pdev, int state)
> }
> EXPORT_SYMBOL(pci_disable_link_state);
>
> +/**
> + * pci_enable_link_state - Re-enable device's link state
> + * @pdev: PCI device
> + * @state: ASPM link states to re-enable
> + *
> + * Enable device's link state that were previously disable so the link is
"state[s] that were previously disable[d]" alludes to the use case you
have in mind, but I don't think it describes how this function
actually works. This function just makes it possible to enable the
specified states. The @state parameter may have nothing to do with
any previously disabled states.
> + * allowed to enter the specific states. Note that if the BIOS didn't grant
> + * ASPM control to the OS, this does nothing because we can't touch the
> + * LNKCTL register.
> + *
> + * Return: 0 or a negative errno.
> + */
> +int pci_enable_link_state(struct pci_dev *pdev, int state)
> +{
> + struct pcie_link_state *link = pcie_aspm_get_link(pdev);
> +
> + if (!link)
> + return -EINVAL;
> + /*
> + * A driver requested that ASPM be enabled on this device, but
> + * if we don't have permission to manage ASPM (e.g., on ACPI
> + * systems we have to observe the FADT ACPI_FADT_NO_ASPM bit and
> + * the _OSC method), we can't honor that request.
> + */
> + if (aspm_disabled) {
> + pci_warn(pdev, "can't enable ASPM; OS doesn't have ASPM control\n");
> + return -EPERM;
> + }
> +
> + mutex_lock(&aspm_lock);
> + link->aspm_disable &= ~pci_link_state_mask(state);
> + pcie_config_aspm_link(link, policy_to_aspm_state(link));
> +
> + if (state & PCIE_LINK_STATE_CLKPM)
> + link->clkpm_disable = 0;
> + pcie_set_clkpm(link, policy_to_clkpm_state(link));
> + mutex_unlock(&aspm_lock);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(pci_enable_link_state);
> +
> /**
> * pci_set_default_link_state - Set the default device link state
> * @pdev: PCI device
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 3c24ca164104..844d09230264 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1776,11 +1776,13 @@ extern bool pcie_ports_native;
> int pci_disable_link_state(struct pci_dev *pdev, int state);
> int pci_disable_link_state_locked(struct pci_dev *pdev, int state);
> #ifdef CONFIG_PCIEASPM
> +int pci_enable_link_state(struct pci_dev *pdev, int state);
> int pci_set_default_link_state(struct pci_dev *pdev, int state);
> void pcie_no_aspm(void);
> bool pcie_aspm_support_enabled(void);
> bool pcie_aspm_enabled(struct pci_dev *pdev);
> #else
> +static inline int pci_enable_link_state(struct pci_dev *pdev, int state) { return -EOPNOTSUPP; }
> static inline int pci_set_default_link_state(struct pci_dev *pdev, int state)
> { return 0; }
> static inline void pcie_no_aspm(void) { }
> --
> 2.30.2
>
>
> --
> ath12k mailing list
> ath12k@lists.infradead.org
> https://lists.infradead.org/mailman/listinfo/ath12k
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next prev parent reply other threads:[~2023-10-11 21:53 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-18 13:10 [PATCH v2 00/13] PCI/ASPM: Make ASPM in core robust and remove driver workarounds Ilpo Järvinen
2023-09-18 13:10 ` [PATCH v2 01/13] PCI/ASPM: Rename pci_enable_link_state() to pci_set_default_link_state() Ilpo Järvinen
2023-09-18 13:10 ` [PATCH v2 02/13] PCI/ASPM: Improve pci_set_default_link_state() kerneldoc Ilpo Järvinen
2023-09-18 13:10 ` [PATCH v2 03/13] PCI/ASPM: Disable ASPM when driver requests it Ilpo Järvinen
2023-10-11 20:04 ` Bjorn Helgaas
2023-10-12 10:47 ` Ilpo Järvinen
2023-10-11 21:22 ` Bjorn Helgaas
2023-10-12 10:56 ` Ilpo Järvinen
2023-10-13 16:42 ` Bjorn Helgaas
2023-10-16 14:27 ` Ilpo Järvinen
2023-10-26 22:02 ` Bjorn Helgaas
2023-09-18 13:10 ` [PATCH v2 04/13] PCI/ASPM: Move L0S/L1/sub states mask calculation into a helper Ilpo Järvinen
2023-10-11 19:32 ` Bjorn Helgaas
2023-10-12 10:29 ` Ilpo Järvinen
2023-09-18 13:10 ` [PATCH v2 05/13] PCI/ASPM: Add pci_enable_link_state() Ilpo Järvinen
2023-10-11 21:53 ` Bjorn Helgaas [this message]
2023-10-12 12:53 ` Ilpo Järvinen
2023-10-13 16:48 ` Bjorn Helgaas
2023-10-16 12:57 ` Ilpo Järvinen
2023-09-18 13:10 ` [PATCH v2 06/13] Bluetooth: hci_bcm4377: Convert aspm disable to quirk Ilpo Järvinen
2023-09-19 13:36 ` Sven Peter
2023-09-18 13:10 ` [PATCH v2 07/13] mt76: Remove unreliable pci_disable_link_state() workaround Ilpo Järvinen
2023-09-18 13:10 ` [PATCH v2 08/13] e1000e: Remove unreliable pci_disable_link_state{,_locked}() workaround Ilpo Järvinen
2023-09-18 13:10 ` [PATCH v2 09/13] wifi: ath10k: Use pci_disable/enable_link_state() Ilpo Järvinen
2023-09-19 9:39 ` Kalle Valo
2023-09-18 13:11 ` [PATCH v2 10/13] wifi: ath11k: " Ilpo Järvinen
2023-09-19 9:40 ` Kalle Valo
2023-09-18 13:11 ` [PATCH v2 11/13] wifi: ath12k: " Ilpo Järvinen
2023-09-19 9:40 ` Kalle Valo
2023-09-18 13:11 ` [PATCH v2 12/13] RDMA/hfi1: " Ilpo Järvinen
2023-09-18 13:11 ` [PATCH v2 13/13] misc: rtsx: " Ilpo Järvinen
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