From: Bjorn Helgaas <helgaas@kernel.org>
To: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
Kalle Valo <kvalo@codeaurora.org>,
Yicong Yang <yangyicong@hisilicon.com>,
linux-pci@vger.kernel.org
Subject: Re: [PATCH] PCI: Make pcie_find_root_port() work for PCIe root ports as well
Date: Tue, 30 Jun 2020 17:01:07 -0500 [thread overview]
Message-ID: <20200630220107.GA3489322@bjorn-Precision-5520> (raw)
In-Reply-To: <20200622161248.51099-1-mika.westerberg@linux.intel.com>
On Mon, Jun 22, 2020 at 07:12:48PM +0300, Mika Westerberg wrote:
> Commit 6ae72bfa656e ("PCI: Unify pcie_find_root_port() and
> pci_find_pcie_root_port()") unified the root port finding functionality
> into a single function but missed the fact that the passed in device may
> already be a root port. This causes the kernel to block power management
> of PCIe hierarchies in recent systems because ->bridge_d3 started to
> return false for such ports after the commit in question.
>
> Fixes: 6ae72bfa656e ("PCI: Unify pcie_find_root_port() and pci_find_pcie_root_port()")
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> Cc: stable@vger.kernel.org
> ---
> include/linux/pci.h | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index c79d83304e52..c17c24f5eeed 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -2169,8 +2169,13 @@ static inline int pci_pcie_type(const struct pci_dev *dev)
> */
> static inline struct pci_dev *pcie_find_root_port(struct pci_dev *dev)
> {
> - struct pci_dev *bridge = pci_upstream_bridge(dev);
> + struct pci_dev *bridge;
>
> + /* If dev is already root port */
> + if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)
> + return dev;
> +
> + bridge = pci_upstream_bridge(dev);
> while (bridge) {
> if (pci_pcie_type(bridge) == PCI_EXP_TYPE_ROOT_PORT)
> return bridge;
I applied the patch below, which is slightly simplified but I think
still equivalent, to for-linus for v5.8. Let me know if it's not.
I dropped the stable tag because 6ae72bfa656e was merged for v5.8-rc1,
and I assume v5.7 works correctly so it doesn't need any change.
commit 5396956cc7c6 ("PCI: Make pcie_find_root_port() work for Root Ports")
Author: Mika Westerberg <mika.westerberg@linux.intel.com>
Date: Mon Jun 22 19:12:48 2020 +0300
PCI: Make pcie_find_root_port() work for Root Ports
Commit 6ae72bfa656e ("PCI: Unify pcie_find_root_port() and
pci_find_pcie_root_port()") broke acpi_pci_bridge_d3() because calling
pcie_find_root_port() on a Root Port returned NULL when it should return
the Root Port, which in turn broke power management of PCIe hierarchies.
Rework pcie_find_root_port() so it returns its argument when it is already
a Root Port.
[bhelgaas: test device only once, test for PCIe]
Fixes: 6ae72bfa656e ("PCI: Unify pcie_find_root_port() and pci_find_pcie_root_port()")
Link: https://lore.kernel.org/r/20200622161248.51099-1-mika.westerberg@linux.intel.com
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/include/linux/pci.h b/include/linux/pci.h
index c79d83304e52..34c1c4f45288 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2169,12 +2169,11 @@ static inline int pci_pcie_type(const struct pci_dev *dev)
*/
static inline struct pci_dev *pcie_find_root_port(struct pci_dev *dev)
{
- struct pci_dev *bridge = pci_upstream_bridge(dev);
-
- while (bridge) {
- if (pci_pcie_type(bridge) == PCI_EXP_TYPE_ROOT_PORT)
- return bridge;
- bridge = pci_upstream_bridge(bridge);
+ while (dev) {
+ if (pci_is_pcie(dev) &&
+ pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)
+ return dev;
+ dev = pci_upstream_bridge(dev);
}
return NULL;
next prev parent reply other threads:[~2020-06-30 22:01 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-22 16:12 [PATCH] PCI: Make pcie_find_root_port() work for PCIe root ports as well Mika Westerberg
2020-06-30 22:01 ` Bjorn Helgaas [this message]
2020-07-01 1:53 ` Yicong Yang
2020-07-01 10:15 ` Mika Westerberg
2020-07-01 12:47 ` Yicong Yang
2020-07-01 10:14 ` Mika Westerberg
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