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authorGrant Grundler <grundler@parisc-linux.org>2006-03-30 07:13:21 +0000
committerKyle McMartin <kyle@hera.kernel.org>2006-04-21 22:20:33 +0000
commitb312c33e362696d873931d8f84a89b3e894077c8 (patch)
tree94f0607b3ee54dfd87c7849f6666d9f68452491a /drivers/parisc
parent67a5a59d3301949f51f2d617d689f005c6d21470 (diff)
downloadlinux-b312c33e362696d873931d8f84a89b3e894077c8.tar.bz2
[PARISC] Document that we tolerate "Relaxed Ordering"
This means "DMA Read returns" can bypass "MMIO Writes". Violating the PCI specs in this case improves outbound DMA "flows" and is currently not required by any drivers. This is NOT a new behavior. Previous chipsets did this already and I believe ZX1 PDC was already setting this for hpux. I just want to further document the behavior. Signed-off-by: Grant Grundler <grundler@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Diffstat (limited to 'drivers/parisc')
-rw-r--r--drivers/parisc/sba_iommu.c45
1 files changed, 32 insertions, 13 deletions
diff --git a/drivers/parisc/sba_iommu.c b/drivers/parisc/sba_iommu.c
index 42b32ff2fca6..278f325021ee 100644
--- a/drivers/parisc/sba_iommu.c
+++ b/drivers/parisc/sba_iommu.c
@@ -178,6 +178,11 @@ extern struct proc_dir_entry * proc_mckinley_root;
#define ROPE6_CTL 0x230
#define ROPE7_CTL 0x238
+#define IOC_ROPE0_CFG 0x500 /* pluto only */
+#define IOC_ROPE_AO 0x10 /* Allow "Relaxed Ordering" */
+
+
+
#define HF_ENABLE 0x40
@@ -1759,19 +1764,33 @@ printk("sba_hw_init(): mem_boot 0x%x 0x%x 0x%x 0x%x\n", PAGE0->mem_boot.hpa,
sba_dev->num_ioc = num_ioc;
for (i = 0; i < num_ioc; i++) {
- /*
- ** Make sure the box crashes if we get any errors on a rope.
- */
- WRITE_REG(HF_ENABLE, sba_dev->ioc[i].ioc_hpa + ROPE0_CTL);
- WRITE_REG(HF_ENABLE, sba_dev->ioc[i].ioc_hpa + ROPE1_CTL);
- WRITE_REG(HF_ENABLE, sba_dev->ioc[i].ioc_hpa + ROPE2_CTL);
- WRITE_REG(HF_ENABLE, sba_dev->ioc[i].ioc_hpa + ROPE3_CTL);
- WRITE_REG(HF_ENABLE, sba_dev->ioc[i].ioc_hpa + ROPE4_CTL);
- WRITE_REG(HF_ENABLE, sba_dev->ioc[i].ioc_hpa + ROPE5_CTL);
- WRITE_REG(HF_ENABLE, sba_dev->ioc[i].ioc_hpa + ROPE6_CTL);
- WRITE_REG(HF_ENABLE, sba_dev->ioc[i].ioc_hpa + ROPE7_CTL);
-
- /* flush out the writes */
+ unsigned long ioc_hpa = sba_dev->ioc[i].ioc_hpa;
+ unsigned int j;
+
+ for (j=0; j < sizeof(u64) * ROPES_PER_IOC; j+=sizeof(u64)) {
+
+ /*
+ * Clear ROPE(N)_CONFIG AO bit.
+ * Disables "NT Ordering" (~= !"Relaxed Ordering")
+ * Overrides bit 1 in DMA Hint Sets.
+ * Improves netperf UDP_STREAM by ~10% for bcm5701.
+ */
+ if (IS_PLUTO(sba_dev->iodc)) {
+ unsigned long rope_cfg, cfg_val;
+
+ rope_cfg = ioc_hpa + IOC_ROPE0_CFG + j;
+ cfg_val = READ_REG(rope_cfg);
+ cfg_val &= ~IOC_ROPE_AO;
+ WRITE_REG(cfg_val, rope_cfg);
+ }
+
+ /*
+ ** Make sure the box crashes on rope errors.
+ */
+ WRITE_REG(HF_ENABLE, ioc_hpa + ROPE0_CTL + j);
+ }
+
+ /* flush out the last writes */
READ_REG(sba_dev->ioc[i].ioc_hpa + ROPE7_CTL);
DBG_INIT(" ioc[%d] ROPE_CFG 0x%Lx ROPE_DBG 0x%Lx\n",