Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=9e1848b60d09a715ff1e19aa6fda47e061d04965
Commit:     9e1848b60d09a715ff1e19aa6fda47e061d04965
Parent:     9de4dfb4c7176e5bb232a21cdd8df78da2b15cac
Author:     David S. Miller <[EMAIL PROTECTED]>
AuthorDate: Thu Jan 3 20:11:31 2008 -0800
Committer:  David S. Miller <[EMAIL PROTECTED]>
CommitDate: Fri Jan 4 03:55:22 2008 -0800

    [CASSINI]: Program parent Intel31154 bridge when necessary.
    
    Signed-off-by: David S. Miller <[EMAIL PROTECTED]>
---
 drivers/net/cassini.c |   86 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 86 insertions(+), 0 deletions(-)

diff --git a/drivers/net/cassini.c b/drivers/net/cassini.c
index 9c77ead..33ac2ef 100644
--- a/drivers/net/cassini.c
+++ b/drivers/net/cassini.c
@@ -4846,6 +4846,90 @@ static int cas_ioctl(struct net_device *dev, struct 
ifreq *ifr, int cmd)
        return rc;
 }
 
+/* When this chip sits underneath an Intel 31154 bridge, it is the
+ * only subordinate device and we can tweak the bridge settings to
+ * reflect that fact.
+ */
+static void __devinit cas_program_bridge(struct pci_dev *cas_pdev)
+{
+       struct pci_dev *pdev = cas_pdev->bus->self;
+       u32 val;
+
+       if (!pdev)
+               return;
+
+       if (pdev->vendor != 0x8086 || pdev->device != 0x537c)
+               return;
+
+       /* Clear bit 10 (Bus Parking Control) in the Secondary
+        * Arbiter Control/Status Register which lives at offset
+        * 0x41.  Using a 32-bit word read/modify/write at 0x40
+        * is much simpler so that's how we do this.
+        */
+       pci_read_config_dword(pdev, 0x40, &val);
+       val &= ~0x00040000;
+       pci_write_config_dword(pdev, 0x40, val);
+
+       /* Max out the Multi-Transaction Timer settings since
+        * Cassini is the only device present.
+        *
+        * The register is 16-bit and lives at 0x50.  When the
+        * settings are enabled, it extends the GRANT# signal
+        * for a requestor after a transaction is complete.  This
+        * allows the next request to run without first needing
+        * to negotiate the GRANT# signal back.
+        *
+        * Bits 12:10 define the grant duration:
+        *
+        *      1       --      16 clocks
+        *      2       --      32 clocks
+        *      3       --      64 clocks
+        *      4       --      128 clocks
+        *      5       --      256 clocks
+        *
+        * All other values are illegal.
+        *
+        * Bits 09:00 define which REQ/GNT signal pairs get the
+        * GRANT# signal treatment.  We set them all.
+        */
+       pci_write_config_word(pdev, 0x50, (5 << 10) | 0x3ff);
+
+       /* The Read Prefecth Policy register is 16-bit and sits at
+        * offset 0x52.  It enables a "smart" pre-fetch policy.  We
+        * enable it and max out all of the settings since only one
+        * device is sitting underneath and thus bandwidth sharing is
+        * not an issue.
+        *
+        * The register has several 3 bit fields, which indicates a
+        * multiplier applied to the base amount of prefetching the
+        * chip would do.  These fields are at:
+        *
+        *      15:13   ---     ReRead Primary Bus
+        *      12:10   ---     FirstRead Primary Bus
+        *      09:07   ---     ReRead Secondary Bus
+        *      06:04   ---     FirstRead Secondary Bus
+        *
+        * Bits 03:00 control which REQ/GNT pairs the prefetch settings
+        * get enabled on.  Bit 3 is a grouped enabler which controls
+        * all of the REQ/GNT pairs from [8:3].  Bits 2 to 0 control
+        * the individual REQ/GNT pairs [2:0].
+        */
+       pci_write_config_word(pdev, 0x52,
+                             (0x7 << 13) |
+                             (0x7 << 10) |
+                             (0x7 <<  7) |
+                             (0x7 <<  4) |
+                             (0xf <<  0));
+
+       /* Force cacheline size to 0x8 */
+       pci_write_config_byte(pdev, PCI_CACHE_LINE_SIZE, 0x08);
+
+       /* Force latency timer to maximum setting so Cassini can
+        * sit on the bus as long as it likes.
+        */
+       pci_write_config_byte(pdev, PCI_LATENCY_TIMER, 0xff);
+}
+
 static int __devinit cas_init_one(struct pci_dev *pdev,
                                  const struct pci_device_id *ent)
 {
@@ -4901,6 +4985,8 @@ static int __devinit cas_init_one(struct pci_dev *pdev,
                printk(KERN_WARNING PFX "Could not enable MWI for %s\n",
                       pci_name(pdev));
 
+       cas_program_bridge(pdev);
+
        /*
         * On some architectures, the default cache line size set
         * by pci_try_set_mwi reduces perforamnce.  We have to increase
-
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