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Date: Wed, 14 Jul 2021 14:04:17 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Joerg Roedel <joro@...tes.org>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
"Rafael J . Wysocki" <rjw@...ysocki.net>,
Len Brown <lenb@...nel.org>,
Linux PCI <linux-pci@...r.kernel.org>,
ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Joerg Roedel <jroedel@...e.de>
Subject: Re: [PATCH v2 1/2] PCI/APCI: Move acpi_pci_osc_support() check to
negotiation phase
On Wed, Jul 14, 2021 at 10:55 AM Joerg Roedel <joro@...tes.org> wrote:
>
> From: Joerg Roedel <jroedel@...e.de>
>
> The acpi_pci_osc_support() does an _OSC query with _OSC supported set
> to what the OS supports but a zero _OSC control value, only to later
> claim the features Linux wants to control with an extra _OSC query.
>
> Nothing between the two _OSC querys depends on the result of the first
> one (if successfull), and if the supported query fails the control
> query will fail too. So it is a good code simplification to combine
> these two querys into one.
>
> As a result the acpi_pci_osc_support() function can be removed and
> acpi_pci_query_osc() be simplified because it no longer called with a
> NULL pointer for *control. Also some code duplication in the existing
> error paths was consolidated.
>
> Signed-off-by: Joerg Roedel <jroedel@...e.de>
> ---
> drivers/acpi/pci_root.c | 114 ++++++++++++++++++----------------------
> 1 file changed, 52 insertions(+), 62 deletions(-)
>
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index d7deedf3548e..c703832b7f7f 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -201,31 +201,20 @@ static acpi_status acpi_pci_query_osc(struct acpi_pci_root *root,
>
> support &= OSC_PCI_SUPPORT_MASKS;
> support |= root->osc_support_set;
> + *control &= OSC_PCI_CONTROL_MASKS;
>
> capbuf[OSC_QUERY_DWORD] = OSC_QUERY_ENABLE;
> capbuf[OSC_SUPPORT_DWORD] = support;
> - if (control) {
> - *control &= OSC_PCI_CONTROL_MASKS;
> - 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;
> @@ -348,7 +337,8 @@ 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 req, u32 support)
> {
> struct acpi_pci_root *root;
> acpi_status status;
> @@ -372,7 +362,7 @@ static acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 *mask, u32 r
>
> /* Need to check the available controls bits before requesting them. */
> while (*mask) {
> - status = acpi_pci_query_osc(root, root->osc_support_set, mask);
> + status = acpi_pci_query_osc(root, support, mask);
> if (ACPI_FAILURE(status))
> return status;
> if (ctrl == *mask)
> @@ -402,7 +392,7 @@ static acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 *mask, u32 r
> 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;
> acpi_status status;
> struct acpi_device *device = root->device;
> acpi_handle handle = device->handle;
> @@ -435,59 +425,49 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm,
> support |= OSC_PCI_EDR_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)
> + if (!pcie_ports_disabled) {
If pcie_ports_disabled is set, we don't want to request any control
from the platform firmware at all and, specifically, we don't want to
evaluate _OSC with the OSC_QUERY_ENABLE clear in
capbuf[OSC_QUERY_DWORD].
I'm not sure how this is achieved after your changes.
> + if ((support & ACPI_PCIE_REQ_SUPPORT) != ACPI_PCIE_REQ_SUPPORT) {
> + decode_osc_support(root, "not requesting OS control; OS requires",
> + ACPI_PCIE_REQ_SUPPORT);
> return;
> + }
>
> - dev_info(&device->dev, "_OSC: platform retains control of PCIe features (%s)\n",
> - acpi_format_exception(status));
> - return;
> - }
> -
> - if (pcie_ports_disabled) {
> - dev_info(&device->dev, "PCIe port services disabled; not requesting _OSC control\n");
> - return;
> - }
> -
> - if ((support & ACPI_PCIE_REQ_SUPPORT) != ACPI_PCIE_REQ_SUPPORT) {
> - decode_osc_support(root, "not requesting OS control; OS requires",
> - ACPI_PCIE_REQ_SUPPORT);
> - return;
> - }
> -
> - control = OSC_PCI_EXPRESS_CAPABILITY_CONTROL
> - | OSC_PCI_EXPRESS_PME_CONTROL;
> + control = OSC_PCI_EXPRESS_CAPABILITY_CONTROL
> + | OSC_PCI_EXPRESS_PME_CONTROL;
>
> - if (IS_ENABLED(CONFIG_PCIEASPM))
> - control |= OSC_PCI_EXPRESS_LTR_CONTROL;
> + if (IS_ENABLED(CONFIG_PCIEASPM))
> + control |= OSC_PCI_EXPRESS_LTR_CONTROL;
>
> - if (IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE))
> - control |= OSC_PCI_EXPRESS_NATIVE_HP_CONTROL;
> + if (IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE))
> + control |= OSC_PCI_EXPRESS_NATIVE_HP_CONTROL;
>
> - if (IS_ENABLED(CONFIG_HOTPLUG_PCI_SHPC))
> - control |= OSC_PCI_SHPC_NATIVE_HP_CONTROL;
> + if (IS_ENABLED(CONFIG_HOTPLUG_PCI_SHPC))
> + control |= OSC_PCI_SHPC_NATIVE_HP_CONTROL;
>
> - if (pci_aer_available())
> - control |= OSC_PCI_EXPRESS_AER_CONTROL;
> + if (pci_aer_available())
> + control |= OSC_PCI_EXPRESS_AER_CONTROL;
>
> - /*
> - * Per the Downstream Port Containment Related Enhancements ECN to
> - * the PCI Firmware Spec, r3.2, sec 4.5.1, table 4-5,
> - * OSC_PCI_EXPRESS_DPC_CONTROL indicates the OS supports both DPC
> - * and EDR.
> - */
> - if (IS_ENABLED(CONFIG_PCIE_DPC) && IS_ENABLED(CONFIG_PCIE_EDR))
> - control |= OSC_PCI_EXPRESS_DPC_CONTROL;
> + /*
> + * Per the Downstream Port Containment Related Enhancements ECN to
> + * the PCI Firmware Spec, r3.2, sec 4.5.1, table 4-5,
> + * OSC_PCI_EXPRESS_DPC_CONTROL indicates the OS supports both DPC
> + * and EDR.
> + */
> + if (IS_ENABLED(CONFIG_PCIE_DPC) && IS_ENABLED(CONFIG_PCIE_EDR))
> + control |= OSC_PCI_EXPRESS_DPC_CONTROL;
> + }
>
> + /* Need an _OSC call even with pcie_ports_disabled set */
> requested = control;
> status = acpi_pci_osc_control_set(handle, &control,
> - OSC_PCI_EXPRESS_CAPABILITY_CONTROL);
> + OSC_PCI_EXPRESS_CAPABILITY_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
> @@ -498,10 +478,8 @@ 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));
> + /* Platform wants to control PCIe features */
> + root->osc_support_set = 0;
>
> /*
> * We want to disable ASPM here, but aspm_disabled
> @@ -511,6 +489,18 @@ 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 (requested) {
> + 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));
> }
> }
>
> --
> 2.31.1
>
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