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    Subject[PATCH v3 4/4] PCI/ACPI: Check for _OSC support in acpi_pci_osc_control_set()
    Date
    From: Joerg Roedel <jroedel@suse.de>

    Get rid of acpi_pci_osc_support() and check for _OSC supported features
    directly in acpi_pci_osc_control_set(). There is no point in doing an
    unconditional _OSC query with control=0 even when the kernel later wants
    to take control over more features.

    This safes one _OSC query and simplifies the code by getting rid of
    the acpi_pci_osc_support() function. As a side effect, the !control
    checks in acpi_pci_query_osc() can also be removed.

    Signed-off-by: Joerg Roedel <jroedel@suse.de>
    ---
    drivers/acpi/pci_root.c | 81 ++++++++++++++++-------------------------
    1 file changed, 32 insertions(+), 49 deletions(-)

    diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
    index f12e512bcddc..ab2f7dfb0c44 100644
    --- a/drivers/acpi/pci_root.c
    +++ b/drivers/acpi/pci_root.c
    @@ -203,26 +203,16 @@ static acpi_status acpi_pci_query_osc(struct acpi_pci_root *root,

    capbuf[OSC_QUERY_DWORD] = OSC_QUERY_ENABLE;
    capbuf[OSC_SUPPORT_DWORD] = support;
    - if (control)
    - capbuf[OSC_CONTROL_DWORD] = *control | root->osc_control_set;
    - else
    - /* Run _OSC query only with existing controls. */
    - capbuf[OSC_CONTROL_DWORD] = root->osc_control_set;
    + capbuf[OSC_CONTROL_DWORD] = *control | root->osc_control_set;

    status = acpi_pci_run_osc(root->device->handle, capbuf, &result);
    if (ACPI_SUCCESS(status)) {
    root->osc_support_set = support;
    - if (control)
    - *control = result;
    + *control = result;
    }
    return status;
    }

    -static acpi_status acpi_pci_osc_support(struct acpi_pci_root *root, u32 flags)
    -{
    - return acpi_pci_query_osc(root, flags, NULL);
    -}
    -
    struct acpi_pci_root *acpi_pci_find_root(acpi_handle handle)
    {
    struct acpi_pci_root *root;
    @@ -345,8 +335,9 @@ EXPORT_SYMBOL_GPL(acpi_get_pci_dev);
    * _OSC bits the BIOS has granted control of, but its contents are meaningless
    * on failure.
    **/
    -static acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 *mask, u32 req)
    +static acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 *mask, u32 support)
    {
    + u32 req = OSC_PCI_EXPRESS_CAPABILITY_CONTROL;
    struct acpi_pci_root *root;
    acpi_status status;
    u32 ctrl, capbuf[3];
    @@ -354,22 +345,16 @@ static acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 *mask, u32 r
    if (!mask)
    return AE_BAD_PARAMETER;

    - ctrl = *mask;
    - if ((ctrl & req) != req)
    - return AE_TYPE;
    -
    root = acpi_pci_find_root(handle);
    if (!root)
    return AE_NOT_EXIST;

    - *mask = ctrl | root->osc_control_set;
    - /* No need to evaluate _OSC if the control was already granted. */
    - if ((root->osc_control_set & ctrl) == ctrl)
    - return AE_OK;
    + ctrl = *mask;
    + *mask |= root->osc_control_set;

    /* Need to check the available controls bits before requesting them. */
    - while (*mask) {
    - status = acpi_pci_query_osc(root, root->osc_support_set, mask);
    + do {
    + status = acpi_pci_query_osc(root, support, mask);
    if (ACPI_FAILURE(status))
    return status;
    if (ctrl == *mask)
    @@ -377,7 +362,11 @@ static acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 *mask, u32 r
    decode_osc_control(root, "platform does not support",
    ctrl & ~(*mask));
    ctrl = *mask;
    - }
    + } while (*mask);
    +
    + /* No need to request _OSC if the control was already granted. */
    + if ((root->osc_control_set & ctrl) == ctrl)
    + return AE_OK;

    if ((ctrl & req) != req) {
    decode_osc_control(root, "not requesting control; platform does not support",
    @@ -470,7 +459,7 @@ static bool os_control_query_checks(struct acpi_pci_root *root, u32 support)
    static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm,
    bool is_pcie)
    {
    - u32 support, control, requested;
    + u32 support, control = 0, requested = 0;
    acpi_status status;
    struct acpi_device *device = root->device;
    acpi_handle handle = device->handle;
    @@ -490,28 +479,15 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm,
    support = calculate_support();

    decode_osc_support(root, "OS supports", support);
    - status = acpi_pci_osc_support(root, support);
    - if (ACPI_FAILURE(status)) {
    - *no_aspm = 1;
    -
    - /* _OSC is optional for PCI host bridges */
    - if ((status == AE_NOT_FOUND) && !is_pcie)
    - return;
    -
    - dev_info(&device->dev, "_OSC: platform retains control of PCIe features (%s)\n",
    - acpi_format_exception(status));
    - return;
    - }
    -
    - if (!os_control_query_checks(root, support))
    - return;

    - requested = control = calculate_control();
    + if (os_control_query_checks(root, support))
    + requested = control = calculate_control();

    - status = acpi_pci_osc_control_set(handle, &control,
    - OSC_PCI_EXPRESS_CAPABILITY_CONTROL);
    + status = acpi_pci_osc_control_set(handle, &control, support);
    if (ACPI_SUCCESS(status)) {
    - decode_osc_control(root, "OS now controls", control);
    + if (control)
    + decode_osc_control(root, "OS now controls", control);
    +
    if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
    /*
    * We have ASPM control, but the FADT indicates that
    @@ -522,11 +498,6 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm,
    *no_aspm = 1;
    }
    } else {
    - decode_osc_control(root, "OS requested", requested);
    - decode_osc_control(root, "platform willing to grant", control);
    - dev_info(&device->dev, "_OSC: platform retains control of PCIe features (%s)\n",
    - acpi_format_exception(status));
    -
    /*
    * We want to disable ASPM here, but aspm_disabled
    * needs to remain in its state from boot so that we
    @@ -535,6 +506,18 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm,
    * root scan.
    */
    *no_aspm = 1;
    +
    + /* _OSC is optional for PCI host bridges */
    + if ((status == AE_NOT_FOUND) && !is_pcie)
    + return;
    +
    + if (control) {
    + decode_osc_control(root, "OS requested", requested);
    + decode_osc_control(root, "platform willing to grant", control);
    + }
    +
    + dev_info(&device->dev, "_OSC: platform retains control of PCIe features (%s)\n",
    + acpi_format_exception(status));
    }
    }

    --
    2.32.0
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