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Subject[PATCH 1/2] PCI-X/PCI-Express read control interfaces
Date
This patch introduces an interface to read and write PCI-X / PCI-Express 
maximum read byte count values from PCI config space. There is a second
function that returns the maximum _designed_ read byte count, which marks the
maximum value for a device, since some drivers try to set MMRBC to the
highest allowed value and rely on such a function.

Signed-off by: Peter Oruba <peter.oruba@amd.com>
Based on patch set by Stephen Hemminger <shemminger@linux-foundation.org>

---
diff -uprN -X linux-2.6.22-rc1.orig/Documentation/dontdiff
linux-2.6.22-rc1.orig/drivers/pci/pci.c linux-2.6.22-rc1/drivers/pci/pci.c
--- linux-2.6.22-rc1.orig/drivers/pci/pci.c 2007-05-14 11:29:39.473498000
+0200
+++ linux-2.6.22-rc1/drivers/pci/pci.c 2007-05-15 11:44:33.804254000 +0200
@@ -1375,6 +1375,170 @@ pci_set_consistent_dma_mask(struct pci_d
#endif

/**
+ * pcix_get_max_mmrbc - get PCI-X maximum designed memory read byte count
+ * @dev: PCI device to query
+ *
+ * Returns mmrbc: maximum designed memory read count in bytes
+ * or appropriate error value.
+ */
+int
+pcix_get_max_mmrbc(struct pci_dev *dev)
+{
+ int ret, err, cap;
+ u32 stat;
+
+ cap = pci_find_capability(dev, PCI_CAP_ID_PCIX);
+ if (!cap)
+ return -EINVAL;
+
+ err = pci_read_config_dword(dev, cap + PCI_X_STATUS, &stat);
+ if (err)
+ return -EINVAL;
+
+ ret = (stat & PCI_X_STATUS_MAX_READ) >> 12;
+
+ return ret;
+}
+EXPORT_SYMBOL(pcix_get_max_mmrbc);
+
+/**
+ * pcix_get_mmrbc - get PCI-X maximum memory read byte count
+ * @dev: PCI device to query
+ *
+ * Returns mmrbc: maximum memory read count in bytes
+ * or appropriate error value.
+ */
+int
+pcix_get_mmrbc(struct pci_dev *dev)
+{
+ int ret, cap;
+ u32 cmd;
+
+ cap = pci_find_capability(dev, PCI_CAP_ID_PCIX);
+ if (!cap)
+ return -EINVAL;
+
+ ret = pci_read_config_dword(dev, cap + PCI_X_CMD, &cmd);
+ if (!ret)
+ ret = 512 << ((cmd & PCI_X_CMD_MAX_READ) >> 2);
+
+ return ret;
+}
+EXPORT_SYMBOL(pcix_get_mmrbc);
+
+/**
+ * pcix_set_mmrbc - set PCI-X maximum memory read byte count
+ * @dev: PCI device to query
+ * @mmrbc: maximum memory read count in bytes
+ * valid values are 512, 1024, 2048, 4096
+ *
+ * If possible sets maximum memory read byte count, some bridges have erratas
+ * that prevent this.
+ */
+int
+pcix_set_mmrbc(struct pci_dev *dev, int mmrbc)
+{
+ int cap, err = -EINVAL;
+ u32 stat, cmd, v, o;
+
+ if (mmrbc < 512 || mmrbc > 4096 || (mmrbc & (mmrbc-1)))
+ goto out;
+
+ v = ffs(mmrbc) - 10;
+
+ cap = pci_find_capability(dev, PCI_CAP_ID_PCIX);
+ if (!cap)
+ goto out;
+
+ err = pci_read_config_dword(dev, cap + PCI_X_STATUS, &stat);
+ if (err)
+ goto out;
+
+ if (v > (stat & PCI_X_STATUS_MAX_READ) >> 21)
+ return -E2BIG;
+
+ err = pci_read_config_dword(dev, cap + PCI_X_CMD, &cmd);
+ if (err)
+ goto out;
+
+ o = (cmd & PCI_X_CMD_MAX_READ) >> 2;
+ if (o != v) {
+ if (v > o && dev->bus &&
+ (dev->bus->bus_flags & PCI_BUS_FLAGS_NO_MMRBC))
+ return -EIO;
+
+ cmd &= ~PCI_X_CMD_MAX_READ;
+ cmd |= v << 2;
+ err = pci_write_config_dword(dev, cap + PCI_X_CMD, cmd);
+ }
+out:
+ return err;
+}
+EXPORT_SYMBOL(pcix_set_mmrbc);
+
+/**
+ * pcie_get_readrq - get PCI Express read request size
+ * @dev: PCI device to query
+ *
+ * Returns maximum memory read request in bytes
+ * or appropriate error value.
+ */
+int pcie_get_readrq(struct pci_dev *dev)
+{
+ int ret, cap;
+ u16 ctl;
+
+ cap = pci_find_capability(dev, PCI_CAP_ID_EXP);
+ if (!cap)
+ return -EINVAL;
+
+ ret = pci_read_config_word(dev, cap + PCI_EXP_DEVCTL, &ctl);
+ if (!ret)
+ ret = 128 << ((ctl & PCI_EXP_DEVCTL_READRQ) >> 12);
+
+ return ret;
+}
+EXPORT_SYMBOL(pcie_get_readrq);
+
+/**
+ * pcie_set_readrq - set PCI Express maximum memory read request
+ * @dev: PCI device to query
+ * @count: maximum memory read count in bytes
+ * valid values are 128, 256, 512, 1024, 2048, 4096
+ *
+ * If possible sets maximum read byte count
+ */
+int
+pcie_set_readrq(struct pci_dev *dev, int rq)
+{
+ int cap, err = -EINVAL;
+ u16 ctl, v;
+
+ if (rq < 128 || rq > 4096 || (rq & (rq-1)))
+ goto out;
+
+ v = (ffs(rq) - 8) << 12;
+
+ cap = pci_find_capability(dev, PCI_CAP_ID_EXP);
+ if (!cap)
+ goto out;
+
+ err = pci_read_config_word(dev, cap + PCI_EXP_DEVCTL, &ctl);
+ if (err)
+ goto out;
+
+ if ((ctl & PCI_EXP_DEVCTL_READRQ) != v) {
+ ctl &= ~PCI_EXP_DEVCTL_READRQ;
+ ctl |= v;
+ err = pci_write_config_dword(dev, cap + PCI_EXP_DEVCTL, ctl);
+ }
+
+out:
+ return err;
+}
+EXPORT_SYMBOL(pcie_set_readrq);
+
+/**
* pci_select_bars - Make BAR mask from the type of resource
* @dev: the PCI device for which BAR mask is made
* @flags: resource type mask to be selected
diff -uprN -X linux-2.6.22-rc1.orig/Documentation/dontdiff
linux-2.6.22-rc1.orig/drivers/pci/quirks.c
linux-2.6.22-rc1/drivers/pci/quirks.c
--- linux-2.6.22-rc1.orig/drivers/pci/quirks.c 2007-05-14 11:29:39.596501000
+0200
+++ linux-2.6.22-rc1/drivers/pci/quirks.c 2007-05-15 10:07:43.342427000 +0200
@@ -627,6 +627,22 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AM
DECLARE_PCI_FIXUP_RESUME(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_8131_BRIDGE,
quirk_amd_8131_ioapic);
#endif /* CONFIG_X86_IO_APIC */

+/*
+ * Some settings of MMRBC can lead to data corruption so block changes.
+ * See AMD 8131 HyperTransport PCI-X Tunnel Revision Guide
+ */
+static void __init quirk_amd_8131_mmrbc(struct pci_dev *dev)
+{
+ unsigned char revid;
+
+ pci_read_config_byte(dev, PCI_REVISION_ID, &revid);
+ if (dev->subordinate && revid <= 0x12) {
+ printk(KERN_INFO "AMD8131 rev %x detected, disabling PCI-X MMRBC\n",
+ revid);
+ dev->subordinate->bus_flags |= PCI_BUS_FLAGS_NO_MMRBC;
+ }
+}
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_8131_BRIDGE,
quirk_amd_8131_mmrbc);

/*
* FIXME: it is questionable that quirk_via_acpi
diff -uprN -X linux-2.6.22-rc1.orig/Documentation/dontdiff
linux-2.6.22-rc1.orig/include/linux/pci.h
linux-2.6.22-rc1/include/linux/pci.h
--- linux-2.6.22-rc1.orig/include/linux/pci.h 2007-05-14 11:29:55.025995000
+0200
+++ linux-2.6.22-rc1/include/linux/pci.h 2007-05-15 11:34:26.602039000 +0200
@@ -111,7 +111,8 @@ enum pcie_reset_state {

typedef unsigned short __bitwise pci_bus_flags_t;
enum pci_bus_flags {
- PCI_BUS_FLAGS_NO_MSI = (__force pci_bus_flags_t) 1,
+ PCI_BUS_FLAGS_NO_MSI = (__force pci_bus_flags_t) 1,
+ PCI_BUS_FLAGS_NO_MMRBC = (__force pci_bus_flags_t) 2,
};

struct pci_cap_saved_state {
@@ -549,6 +550,10 @@ void pci_intx(struct pci_dev *dev, int e
void pci_msi_off(struct pci_dev *dev);
int pci_set_dma_mask(struct pci_dev *dev, u64 mask);
int pci_set_consistent_dma_mask(struct pci_dev *dev, u64 mask);
+int pcix_get_max_mmrbc(struct pci_dev *dev);
+int pcix_get_mmrbc(struct pci_dev *dev);
+int pcix_set_mmrbc(struct pci_dev *dev, int mmrbc);
+int pcie_set_readrq(struct pci_dev *dev, int rq);
void pci_update_resource(struct pci_dev *dev, struct resource *res, int
resno);
int __must_check pci_assign_resource(struct pci_dev *dev, int i);
int __must_check pci_assign_resource_fixed(struct pci_dev *dev, int i);
---
--
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Register Court Dresden: HRA 4896
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