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SubjectRe: [PATCH v2] ACPI: use MSI_NOT_SUPPORTED bit
On Wed, 15 Nov 2006 19:44:12 +0100 Andi Kleen wrote:

> On Wednesday 15 November 2006 19:35, Randy Dunlap wrote:
> > On 15 Nov 2006 05:49:41 +0100 Andi Kleen wrote:
> >
> > > BTW there seems to be a new ACPI FADT bit that says "MSI is broken"
> > > We should probably check that too as a double check.
> >
> > Do you mean more than just use that bit when you say "double check"?
> >
> > I wonder why this hasn't already been done. (?)
>
> Nobody coded it yet.
>
> > How's this look? Build-tested only.
>
> There should be probably a command line option to overwrite it

OK, anything else?

---
From: Randy Dunlap <randy.dunlap@oracle.com>
- Implement use of FADT boot_flags.MSI_NOT_SUPPORTED bit to prevent
assigning MSIs.
- Force MSI_NOT_SUPPORTED for ACPI 1.0 tables.
- Add "pci=allowmsi" to override (ignore) the MSI_NOT_SUPPORTED bit
from the APCI FADT.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
---
Documentation/kernel-parameters.txt | 6 ++++++
drivers/acpi/bus.c | 7 +++++++
drivers/acpi/tables/tbconvrt.c | 3 ++-
drivers/pci/pci.c | 4 ++++
include/acpi/actbl.h | 4 +++-
include/linux/pci.h | 3 +++
6 files changed, 25 insertions(+), 2 deletions(-)
--- linux-2619-rc5.orig/include/acpi/actbl.h
+++ linux-2619-rc5/include/acpi/actbl.h
@@ -290,7 +290,7 @@ struct fadt_descriptor_rev1 {
ACPI_FADT_COMMON u32 flags;
};

-/* FADT: Prefered Power Management Profiles */
+/* FADT: Preferred Power Management Profiles */

#define PM_UNSPECIFIED 0
#define PM_DESKTOP 1
@@ -304,6 +304,8 @@ struct fadt_descriptor_rev1 {

#define BAF_LEGACY_DEVICES 0x0001
#define BAF_8042_KEYBOARD_CONTROLLER 0x0002
+#define BAF_VGA_NOT_PRESENT 0x0004
+#define BAF_MSI_NOT_SUPPORTED 0x0008

#define FADT2_REVISION_ID 3
#define FADT2_MINUS_REVISION_ID 2
--- linux-2619-rc5.orig/drivers/acpi/tables/tbconvrt.c
+++ linux-2619-rc5/drivers/acpi/tables/tbconvrt.c
@@ -289,7 +289,8 @@ acpi_tb_convert_fadt1(struct fadt_descri
* Since there isn't any equivalence in 1.0 and since it is highly
* likely that a 1.0 system has legacy support.
*/
- local_fadt->iapc_boot_arch = BAF_LEGACY_DEVICES;
+ local_fadt->iapc_boot_arch = BAF_LEGACY_DEVICES |
+ BAF_MSI_NOT_SUPPORTED;
}

/*
--- linux-2619-rc5.orig/include/linux/pci.h
+++ linux-2619-rc5/include/linux/pci.h
@@ -610,6 +610,7 @@ static inline int pci_enable_msix(struct
struct msix_entry *entries, int nvec) {return -1;}
static inline void pci_disable_msix(struct pci_dev *dev) {}
static inline void msi_remove_pci_irq_vectors(struct pci_dev *dev) {}
+static inline void pci_no_msi(void) {}
#else
extern void pci_scan_msi_device(struct pci_dev *dev);
extern int pci_enable_msi(struct pci_dev *dev);
@@ -618,6 +619,8 @@ extern int pci_enable_msix(struct pci_de
struct msix_entry *entries, int nvec);
extern void pci_disable_msix(struct pci_dev *dev);
extern void msi_remove_pci_irq_vectors(struct pci_dev *dev);
+extern void pci_no_msi(void);
+extern int pci_allow_msi;
#endif

#ifdef CONFIG_HT_IRQ
--- linux-2619-rc5.orig/drivers/acpi/bus.c
+++ linux-2619-rc5/drivers/acpi/bus.c
@@ -28,6 +28,7 @@
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/sched.h>
+#include <linux/pci.h>
#include <linux/pm.h>
#include <linux/pm_legacy.h>
#include <linux/device.h>
@@ -637,6 +638,12 @@ void __init acpi_early_init(void)
}
#endif

+ if (!pci_allow_msi &&
+ (acpi_fadt.iapc_boot_arch & BAF_MSI_NOT_SUPPORTED)) {
+ printk(KERN_DEBUG PREFIX "MSI not supported, disabling it\n");
+ pci_no_msi();
+ }
+
status =
acpi_enable_subsystem(~
(ACPI_NO_HARDWARE_INIT |
--- linux-2619-rc5.orig/Documentation/kernel-parameters.txt
+++ linux-2619-rc5/Documentation/kernel-parameters.txt
@@ -1178,6 +1178,12 @@ and is between 256 and 4096 characters.
nomsi [MSI] If the PCI_MSI kernel config parameter is
enabled, this kernel boot option can be used to
disable the use of MSI interrupts system-wide.
+ allowmsi [MSI,ACPI] If ACPI FADT says that MSI is not
+ supported on this platform but the user wants
+ to use it anyway, this option tells the kernel
+ to ignore the ACPI FADT MSI flag and allow MSI
+ to be used if there are devices that want to
+ use it.
nosort [IA-32] Don't sort PCI devices according to
order given by the PCI BIOS. This sorting is
done to get a device order compatible with
--- linux-2619-rc5.orig/drivers/pci/pci.c
+++ linux-2619-rc5/drivers/pci/pci.c
@@ -20,6 +20,8 @@
#include "pci.h"

unsigned int pci_pm_d3_delay = 10;
+int pci_allow_msi; /* when set, this overrides the ACPI FADT boot_arch
+ * MSI_NOT_SUPPORTED bit so that MSI can still be used */

/**
* pci_bus_max_busnr - returns maximum PCI bus number of given bus' children
@@ -998,6 +1000,8 @@ static int __devinit pci_setup(char *str
if (*str && (str = pcibios_setup(str)) && *str) {
if (!strcmp(str, "nomsi")) {
pci_no_msi();
+ } else if (!strcmp(str, "allowmsi"))
+ pci_allow_msi = 1;
} else {
printk(KERN_ERR "PCI: Unknown option `%s'\n",
str);
-
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