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authorGrant Grundler <grundler@parisc-linux.org>2006-03-30 02:13:21 -0500
committerKyle McMartin <kyle@hera.kernel.org>2006-04-21 18:20:33 -0400
commitb312c33e362696d873931d8f84a89b3e894077c8 (patch)
tree94f0607b3ee54dfd87c7849f6666d9f68452491a
parent67a5a59d3301949f51f2d617d689f005c6d21470 (diff)
[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>
-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;
178#define ROPE6_CTL 0x230 178#define ROPE6_CTL 0x230
179#define ROPE7_CTL 0x238 179#define ROPE7_CTL 0x238
180 180
181#define IOC_ROPE0_CFG 0x500 /* pluto only */
182#define IOC_ROPE_AO 0x10 /* Allow "Relaxed Ordering" */
183
184
185
181#define HF_ENABLE 0x40 186#define HF_ENABLE 0x40
182 187
183 188
@@ -1759,19 +1764,33 @@ printk("sba_hw_init(): mem_boot 0x%x 0x%x 0x%x 0x%x\n", PAGE0->mem_boot.hpa,
1759 1764
1760 sba_dev->num_ioc = num_ioc; 1765 sba_dev->num_ioc = num_ioc;
1761 for (i = 0; i < num_ioc; i++) { 1766 for (i = 0; i < num_ioc; i++) {
1762 /* 1767 unsigned long ioc_hpa = sba_dev->ioc[i].ioc_hpa;
1763 ** Make sure the box crashes if we get any errors on a rope. 1768 unsigned int j;
1764 */ 1769
1765 WRITE_REG(HF_ENABLE, sba_dev->ioc[i].ioc_hpa + ROPE0_CTL); 1770 for (j=0; j < sizeof(u64) * ROPES_PER_IOC; j+=sizeof(u64)) {
1766 WRITE_REG(HF_ENABLE, sba_dev->ioc[i].ioc_hpa + ROPE1_CTL); 1771
1767 WRITE_REG(HF_ENABLE, sba_dev->ioc[i].ioc_hpa + ROPE2_CTL); 1772 /*
1768 WRITE_REG(HF_ENABLE, sba_dev->ioc[i].ioc_hpa + ROPE3_CTL); 1773 * Clear ROPE(N)_CONFIG AO bit.
1769 WRITE_REG(HF_ENABLE, sba_dev->ioc[i].ioc_hpa + ROPE4_CTL); 1774 * Disables "NT Ordering" (~= !"Relaxed Ordering")
1770 WRITE_REG(HF_ENABLE, sba_dev->ioc[i].ioc_hpa + ROPE5_CTL); 1775 * Overrides bit 1 in DMA Hint Sets.
1771 WRITE_REG(HF_ENABLE, sba_dev->ioc[i].ioc_hpa + ROPE6_CTL); 1776 * Improves netperf UDP_STREAM by ~10% for bcm5701.
1772 WRITE_REG(HF_ENABLE, sba_dev->ioc[i].ioc_hpa + ROPE7_CTL); 1777 */
1773 1778 if (IS_PLUTO(sba_dev->iodc)) {
1774 /* flush out the writes */ 1779 unsigned long rope_cfg, cfg_val;
1780
1781 rope_cfg = ioc_hpa + IOC_ROPE0_CFG + j;
1782 cfg_val = READ_REG(rope_cfg);
1783 cfg_val &= ~IOC_ROPE_AO;
1784 WRITE_REG(cfg_val, rope_cfg);
1785 }
1786
1787 /*
1788 ** Make sure the box crashes on rope errors.
1789 */
1790 WRITE_REG(HF_ENABLE, ioc_hpa + ROPE0_CTL + j);
1791 }
1792
1793 /* flush out the last writes */
1775 READ_REG(sba_dev->ioc[i].ioc_hpa + ROPE7_CTL); 1794 READ_REG(sba_dev->ioc[i].ioc_hpa + ROPE7_CTL);
1776 1795
1777 DBG_INIT(" ioc[%d] ROPE_CFG 0x%Lx ROPE_DBG 0x%Lx\n", 1796 DBG_INIT(" ioc[%d] ROPE_CFG 0x%Lx ROPE_DBG 0x%Lx\n",