Messages in this thread | | | Subject | Re: [RFC PATCH] PCI/APCI: Move acpi_pci_osc_support() check to negotiation phase | From | "Kuppuswamy, Sathyanarayanan" <> | Date | Wed, 28 Apr 2021 10:21:12 -0700 |
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On 4/28/21 1:18 AM, Joerg Roedel wrote: > From: Joerg Roedel <jroedel@suse.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. This is > problematic on some platforms where the firmware allows to configure > whether DPC is under OS or Firmware control.
Do we run acpi_pci_osc_support() only to check whether _OSC is supported ? Or does it serve any other purpose.
> > When DPC is configured to be under OS control these platforms will > issue a warning in the firmware log that the OS does not support DPC.
Also, is there any other benefit from this patch other than fixing a warning message in firmware?
> > Avoid an _OSC query with _OSC control set to zero by moving the > supported check into the acpi_pci_osc_control_set() path. This is > still early enough to fail as nothing before that depends on the > results of acpi_pci_osc_support(). > > 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. > > Signed-off-by: Joerg Roedel <jroedel@suse.de> > --- > drivers/acpi/pci_root.c | 50 ++++++++++++++++------------------------- > 1 file changed, 19 insertions(+), 31 deletions(-) > > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c > index dcd593766a64..530ecf4970b1 100644 > --- a/drivers/acpi/pci_root.c > +++ b/drivers/acpi/pci_root.c > @@ -199,16 +199,11 @@ 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)) { > @@ -219,11 +214,6 @@ static acpi_status acpi_pci_query_osc(struct acpi_pci_root *root, > 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; > @@ -346,7 +336,8 @@ 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; > @@ -370,7 +361,7 @@ 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) > @@ -433,18 +424,6 @@ 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) > - 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"); > @@ -483,7 +462,8 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm, > > 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 (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) { > @@ -496,10 +476,8 @@ 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 > @@ -509,6 +487,16 @@ 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; > + > + 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)); > + > } > } > >
-- Sathyanarayanan Kuppuswamy Linux Kernel Developer
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