> -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf Of > Rafael J. Wysocki > Sent: Thursday, January 11, 2018 12:39 PM > To: Ghannam, Yazen <[email protected]> > Cc: ACPI Devel Maling List <[email protected]>; Linux Kernel Mailing > List <[email protected]>; Linux PCI <[email protected]>; > Rafael J. Wysocki <[email protected]>; Len Brown <[email protected]>; Bjorn > Helgaas <[email protected]>; Borislav Petkov <[email protected]> > Subject: Re: [PATCH] PCI/ACPI: Disable AER when _OSC control bit is clear. > > On Thu, Jan 11, 2018 at 4:03 PM, Yazen Ghannam > <[email protected]> wrote: > > From: Yazen Ghannam <[email protected]> > > > > Currently, aer_service_init() checks if AER is available and that > > Firmware First handling is not enabled. The _OSC request for AER is > > not taken into account when deciding to enable AER in Linux. > > > > We should check that the _OSC control for AER is set. If it's not > > then AER should be disabled. > > > > The _OSC control for AER is not requested when APEI Firmware First is > > used, so the same condition applies. > > > > Mark AER as disabled if the _OSC request was not made or accepted. > > > > Remove redunant check for aer_acpi_firmware_first() when calling > > aer_service_init(), since this is check is already included when > > checking the _OSC control. > > > > Signed-off-by: Yazen Ghannam <[email protected]> > > --- > > drivers/acpi/pci_root.c | 3 +++ > > drivers/pci/pcie/aer/aerdrv.c | 2 +- > > 2 files changed, 4 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c > > index 6fc204a52493..19a625ed8de9 100644 > > --- a/drivers/acpi/pci_root.c > > +++ b/drivers/acpi/pci_root.c > > @@ -512,6 +512,9 @@ static void negotiate_os_control(struct > acpi_pci_root *root, int *no_aspm) > > */ > > *no_aspm = 1; > > } > > + > > + if (!(requested & control & OSC_PCI_EXPRESS_AER_CONTROL)) > > One of the operators above needs to be a && I suppose? >
It's a 3-way bitwise AND to check that OSC_PCI_EXPRESS_AER_CONTROL is set in both "requested" and "control". IOW, we check if AER was requested by the OS and that the platform granted the request. Thanks, Yazen
