From: Bjorn Helgaas <helgaas@kernel.org>
To: Ajay Agarwal <ajayagarwal@google.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com>,
Vidya Sagar <vidyas@nvidia.com>,
Nikhil Devshatwar <nikhilnd@google.com>,
Manu Gautam <manugautam@google.com>,
"David E. Box" <david.e.box@linux.intel.com>,
Kai-Heng Feng <kai.heng.feng@canonical.com>,
Michael Bottini <michael.a.bottini@linux.intel.com>,
linux-pci@vger.kernel.org
Subject: Re: [PATCH 1/3] PCI/ASPM: Disable ASPM_STATE_L1 only when class driver disables L1 ASPM
Date: Mon, 1 May 2023 12:21:14 -0500 [thread overview]
Message-ID: <20230501172114.GA591899@bhelgaas> (raw)
In-Reply-To: <20230411111034.1473044-2-ajayagarwal@google.com>
On Tue, Apr 11, 2023 at 04:40:32PM +0530, Ajay Agarwal wrote:
> Currently the aspm driver sets ASPM_STATE_L1 as well as
> ASPM_STATE_L1SS bits when the class driver disables L1.
I would have said just "driver" -- do you mean something different by
using "class driver"? The callers I see are garden-variety drivers
for individual devices like hci_bcm4377, xillybus_pcie, e1000e, jme,
etc.
> pcie_config_aspm_link takes care that L1ss ASPM is not enabled
> if L1 is disabled. ASPM_STATE_L1SS bits do not need to be
> explicitly set. The sysfs node store() function, which also
> modifies the aspm_disable value, does not set these bits either
> when only L1 ASPM is disabled by the user.
Right. It'd be nice to combine __pci_disable_link_state() and
aspm_attr_store_common() so they use the same logic for this, but
that's not really trivial to do.
> Disable ASPM_STATE_L1 only when class driver disables L1 ASPM.
So IIUC, this is a cleanup and should not fix any actual function
bugs, right? If it *does* fix a bug, we should add a Fixes: tag and a
description of the bug.
> Signed-off-by: Ajay Agarwal <ajayagarwal@google.com>
> ---
> drivers/pci/pcie/aspm.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
> index 66d7514ca111..5765b226102a 100644
> --- a/drivers/pci/pcie/aspm.c
> +++ b/drivers/pci/pcie/aspm.c
> @@ -1095,8 +1095,7 @@ static int __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem)
> if (state & PCIE_LINK_STATE_L0S)
> link->aspm_disable |= ASPM_STATE_L0S;
> if (state & PCIE_LINK_STATE_L1)
> - /* L1 PM substates require L1 */
> - link->aspm_disable |= ASPM_STATE_L1 | ASPM_STATE_L1SS;
> + link->aspm_disable |= ASPM_STATE_L1;
> if (state & PCIE_LINK_STATE_L1_1)
> link->aspm_disable |= ASPM_STATE_L1_1;
> if (state & PCIE_LINK_STATE_L1_2)
> --
> 2.40.0.577.gac1e443424-goog
>
next prev parent reply other threads:[~2023-05-01 17:21 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-11 11:10 [PATCH 0/3] ASPM: aspm_disable/default/support state handling fixes Ajay Agarwal
2023-04-11 11:10 ` [PATCH 1/3] PCI/ASPM: Disable ASPM_STATE_L1 only when class driver disables L1 ASPM Ajay Agarwal
2023-05-01 17:21 ` Bjorn Helgaas [this message]
2023-05-02 12:38 ` Ajay Agarwal
2023-05-02 16:07 ` Bjorn Helgaas
2023-05-02 18:32 ` Ajay Agarwal
2023-04-11 11:10 ` [PATCH 2/3] PCI/ASPM: Set ASPM_STATE_L1 when class driver enables L1ss Ajay Agarwal
2023-05-01 17:44 ` Bjorn Helgaas
2023-05-02 13:02 ` Ajay Agarwal
2023-05-02 16:02 ` Bjorn Helgaas
2023-05-02 18:44 ` Ajay Agarwal
2023-04-11 11:10 ` [PATCH 3/3] PCI/ASPM: Remove unnecessary ASPM_STATE_L1SS check Ajay Agarwal
2023-05-01 17:55 ` Bjorn Helgaas
2023-05-02 13:07 ` Ajay Agarwal
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