There are bugs in ACS implementations by certain switch vendors that
cause ACS violations in perfectly normal accesses. This patch provides
the framework for enabling and disabling the functionality at certain
points during endpoint bringup in the form of a quirk.
Signed-off-by: James Puthukattukaran <james.puthukattukaran@xxxxxxxxxx>
--
-v2: move workaround to pci_bus_read_dev_vendor_id() from
pci_bus_check_dev()
and move enable_acs_sv to drivers/pci/pci.c -- by Yinghai
-v3: add bus->self check for root bus and virtual bus for sriov vfs.
-v4: only do workaround for IDT switches
-v5: tweak pci_std_enable_acs_sv to deal with unimplemented SV
-v6: Added errata verbiage verbatim and resolved patch format issues
-v7: changed int to bool for found and idt_workaround declarations. Also
added bugzilla https://bugzilla.kernel.org/show_bug.cgi?id=196979
-v8: Rewrote the patch by adding a new acs quirk to keep the workaround
out of the main code path
-v9: changed function name from pci_dev_specific_fixup_acs_quirk to
pci_bus_acs_quirk. Also, tested for FLR and hot reset scenarios
and did
not see issues where workaround was required. The issue seems to be
related only to cold reset/power on situation.
-v10: Moved the contents of pci_bus_read_vendor_id into an internal function
__pci_bus_read_vendor_id
-v11: Split the patch into two patches. The first a general quirk framework.
---
drivers/pci/pci.h | 7 +++++++
drivers/pci/probe.c | 33 ++++++++++++++++++++++++++++-----
drivers/pci/quirks.c | 41 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 76 insertions(+), 5 deletions(-)
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 023f7cf..a9e2a8c 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -387,11 +387,18 @@ struct pci_dev_reset_methods {
#ifdef CONFIG_PCI_QUIRKS
int pci_dev_specific_reset(struct pci_dev *dev, int probe);
+int pci_bus_specific_acs_quirk(struct pci_bus *bus , int devfn,
+ int enable, bool found);
#else
static inline int pci_dev_specific_reset(struct pci_dev *dev, int probe)
{
return -ENOTTY;
}
+static inline int pci_bus_specific_acs_quirk(struct pc_bus *bus,
+ int devfn, int enable, bool found)
+{
+ return -ENOTTY;
+}
#endif
#if defined(CONFIG_PCI_QUIRKS) && defined(CONFIG_ARM64)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index ac91b6f..0c93b3e 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2097,21 +2097,44 @@ static bool pci_bus_wait_crs(struct pci_bus
*bus, int devfn, u32 *l,
return true;
}
-bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,
+static bool __pci_bus_read_dev_vendor_id(struct pci_bus *bus, int
devfn, u32 *l,
int timeout)
{
+
+ int found = false;
+
if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, l))
- return false;
+ goto out;
/* Some broken boards return 0 or ~0 if a slot is empty: */
if (*l == 0xffffffff || *l == 0x00000000 ||
*l == 0x0000ffff || *l == 0xffff0000)
- return false;
+ goto out;
+ found = true;
if (pci_bus_crs_vendor_id(*l))
- return pci_bus_wait_crs(bus, devfn, l, timeout);
+ found = pci_bus_wait_crs(bus, devfn, l, timeout);
- return true;
+out:
+ return found;
+
+}
+
+
+bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,
+ int timeout)
+{
+ bool ret;
+ int enable = -1;
+
+ enable = pci_bus_specific_acs_quirk(bus, devfn, false, false);
+
+ ret = __pci_bus_read_dev_vendor_id(bus, devfn, l, timeout);
+
+ if (enable > 0)
+ pci_bus_specific_acs_quirk(bus, devfn, enable, ret);
+
+ return ret;
}
EXPORT_SYMBOL(pci_bus_read_dev_vendor_id);
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 26141b1..bf423e3 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -4737,3 +4737,44 @@ static void quirk_gpu_hda(struct pci_dev *hda)
PCI_CLASS_MULTIMEDIA_HD_AUDIO, 8, quirk_gpu_hda);
DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID,
PCI_CLASS_MULTIMEDIA_HD_AUDIO, 8, quirk_gpu_hda);
+
+
+
+static const struct pci_dev_acs_quirk{
+ u16 vendor;
+ u16 device;
+ int (*acs_quirk)(struct pci_bus *bus, int devfn, int enable, bool found);
+} pci_dev_acs_quirks[] = {
+ {0}
+};
+
+int pci_bus_specific_acs_quirk(struct pci_bus *bus, int devfn, int enable,
+ bool found)
+{
+ const struct pci_dev_acs_quirk *i;
+ struct pci_dev *dev;
+ int ret;
+
+ if (!bus || !bus->self)
+ return -ENOTTY;
+
+ dev = bus->self;
+
+ /*
+ * Allow devices that have HW bugs in the ACS implementations to
+ * control enabling or disabling that ACS feature here.
+ */
+ for (i = pci_dev_acs_quirks; i->acs_quirk; i++) {
+ if ((i->vendor == dev->vendor ||
+ i->vendor == (u16)PCI_ANY_ID) &&
+ (i->device == dev->device ||
+ i->device == (u16)PCI_ANY_ID)) {
+ ret = i->acs_quirk(bus, devfn, enable, found);
+ if (ret >= 0)
+ return ret;
+ }
+ }
+
+ return -ENOTTY;
+}
+
