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    SubjectRe: Aw: Re: Re: [PATCH] pci: mediatek: fix warning in msi.h
    Date
    Frank,

    On Wed, Nov 04 2020 at 17:49, Frank Wunderlich wrote:
    >> Von: "Thomas Gleixner" <tglx@linutronix.de>
    >> Any architecture which selects PCI_MSI_ARCH_FALLBACKS and does not have
    >> irqdomain support runs into:
    >>
    >> if (!d)
    >> bus->bus_flags |= PCI_BUS_FLAGS_NO_MSI;
    >>
    >> which in turn makes pci_msi_supported() return 0 and consequently makes
    >> pci_enable_msi[x]() fail.
    >
    > i'm not that deep into this, but just my thoughts...you are the experts :)
    >
    > checking for PCI_MSI_ARCH_FALLBACKS here does not help?
    >
    > something like this:
    >
    > #ifndef PCI_MSI_ARCH_FALLBACKS
    > if (!d)
    > bus->bus_flags |= PCI_BUS_FLAGS_NO_MSI;
    > #endif

    TBH, that's butt ugly. So after staring long enough into the PCI code I
    came up with a way to transport that information to the probe code.

    That allows a particular device to say 'I can't do MSI' and at the same
    time keeps the warning machinery intact which tells us that a particular
    host controller driver is broken.

    Uncompiled and untested as usual :)

    Thanks,

    tglx
    ---
    drivers/pci/controller/pcie-mediatek.c | 4 ++++
    drivers/pci/probe.c | 3 +++
    include/linux/pci.h | 1 +
    3 files changed, 8 insertions(+)

    --- a/drivers/pci/controller/pcie-mediatek.c
    +++ b/drivers/pci/controller/pcie-mediatek.c
    @@ -143,6 +143,7 @@ struct mtk_pcie_port;
    * struct mtk_pcie_soc - differentiate between host generations
    * @need_fix_class_id: whether this host's class ID needed to be fixed or not
    * @need_fix_device_id: whether this host's device ID needed to be fixed or not
    + * @no_msi: Bridge has no MSI support
    * @device_id: device ID which this host need to be fixed
    * @ops: pointer to configuration access functions
    * @startup: pointer to controller setting functions
    @@ -151,6 +152,7 @@ struct mtk_pcie_port;
    struct mtk_pcie_soc {
    bool need_fix_class_id;
    bool need_fix_device_id;
    + bool no_msi;
    unsigned int device_id;
    struct pci_ops *ops;
    int (*startup)(struct mtk_pcie_port *port);
    @@ -1084,6 +1086,7 @@ static int mtk_pcie_probe(struct platfor

    host->ops = pcie->soc->ops;
    host->sysdata = pcie;
    + host->no_msi = pcie->soc->no_msi;

    err = pci_host_probe(host);
    if (err)
    @@ -1173,6 +1176,7 @@ static const struct dev_pm_ops mtk_pcie_
    };

    static const struct mtk_pcie_soc mtk_pcie_soc_v1 = {
    + .no_msi = true,
    .ops = &mtk_pcie_ops,
    .startup = mtk_pcie_startup_port,
    };
    --- a/drivers/pci/probe.c
    +++ b/drivers/pci/probe.c
    @@ -889,6 +889,9 @@ static int pci_register_host_bridge(stru
    if (!bus)
    return -ENOMEM;

    + if (bridge->no_msi)
    + bus->bus_flags |= PCI_BUS_FLAGS_NO_MSI;
    +
    bridge->bus = bus;

    /* Temporarily move resources off the list */
    --- a/include/linux/pci.h
    +++ b/include/linux/pci.h
    @@ -545,6 +545,7 @@ struct pci_host_bridge {
    unsigned int native_dpc:1; /* OS may use PCIe DPC */
    unsigned int preserve_config:1; /* Preserve FW resource setup */
    unsigned int size_windows:1; /* Enable root bus sizing */
    + unsigned int no_msi:1; /* Bridge has no MSI support */

    /* Resource alignment requirements */
    resource_size_t (*align_resource)(struct pci_dev *dev,
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