2.6.1 enable PIOW/DMAR relaxed ordering on ZX1

Tony, David,
I lied. Apologies. I thought I had sent this patch before but was just confused by the change in my local bk tree. I had the patch sitting there since September. :^(

This enables DMA Reads to bypass PIO Writes for all PCI/PCI-X devices. On older RHAS (2.1 orig), this improved netperf UDP Stream by ~10%. Testing on kernel.org 2.4 kernels showed only ~3-5% improvement. I suspect because of improvements to tg3 driver.

diff is against http://lia64.bkbits.net/linux-ia64-2.6/

thanks,
grant

=== arch/ia64/hp/common/sba_iommu.c 1.33 vs edited ==--- 1.33/arch/ia64/hp/common/sba_iommu.c Fri Sep 19 08:03:40 2003
+++ edited/arch/ia64/hp/common/sba_iommu.c Thu Jan 22 13:25:17 2004
@@ -156,6 +156,10 @@
#define IOC_TCNFG 0x318
#define IOC_PDIR_BASE 0x320

+#define IOC_ROPE0_CFG 0x500
+#define IOC_ROPE_AO 0x10 /* Allow "Relaxed Ordering" */
+
+
/* AGP GART driver looks for this */
#define ZX1_SBA_IOMMU_COOKIE 0x0000badbadc0ffeeUL

@@ -1421,6 +1425,7 @@
#ifdef FULL_VALID_PDIR
unsigned long index;
#endif
+ unsigned int i;

/*
** Firmware programs the base and size of a "safe IOVA space"
@@ -1475,6 +1480,18 @@
** can't reprogram them the way drivers want.
*/
WRITE_REG(ioc->imask, ioc->ioc_hpa + IOC_IMASK);
+
+ /* 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 tg3 on bcm5701.
+ */
+ for (i=0; i<(8*8); i+=8) {
+ unsigned long rope_config;
+ rope_config = READ_REG(ioc->ioc_hpa + IOC_ROPE0_CFG + i);
+ rope_config &= ~IOC_ROPE_AO;
+ WRITE_REG(rope_config, ioc->ioc_hpa + IOC_ROPE0_CFG + i);
+ }

/*
** Setting the upper bits makes checking for bypass addresses

Grant> Tony, David, I lied. Apologies. I thought I had sent this Grant> patch before but was just confused by the change in my local Grant> bk tree. I had the patch sitting there since September. :^(

Grant> This enables DMA Reads to bypass PIO Writes for all PCI/PCI-X Grant> devices. On older RHAS (2.1 orig), this improved netperf UDP Grant> Stream by ~10%. Testing on kernel.org 2.4 kernels showed Grant> only ~3-5% improvement. I suspect because of improvements to Grant> tg3 driver.

Grant> diff is against http://lia64.bkbits.net/linux-ia64-2.6/

I'm not sure Tony's tree is ready for prime-time yet. Could you please diff against my tree instead (linux-ia64-2.5)? I'd have merged the patch by hand, but the context in the patch you posted doesn't look like anything that appears in the current sba_iommu.c.

Thanks,

	--david

In the U.K. (where I'm from originally) people learning to drive must display a large "L" (for "Learning driver") on their car to warn other motorists that they may make erratic moves.

In the bitkeeper world, I'm still learning ... so keep a safe distance from my tree until I pass my proficiency exam.

-Tony

yes - sorry. Patch appended.

hrm...they shouldn't be that different.
OIC. Some of the DMA hint register support was removed. If you want to finish that job, remove the definition and references to hint_mask_pdir and hint_shift_pdir. I'll maintain DMA hints as a seperate patch (2.4 only so far) until I have data it's useful.

thanks,
grant

=== arch/ia64/hp/common/sba_iommu.c 1.35 vs edited ==--- 1.35/arch/ia64/hp/common/sba_iommu.c Mon Jan 12 08:02:23 2004
+++ edited/arch/ia64/hp/common/sba_iommu.c Mon Jan 26 08:47:02 2004
@@ -158,6 +158,10 @@
#define IOC_TCNFG 0x318
#define IOC_PDIR_BASE 0x320

+#define IOC_ROPE0_CFG 0x500
+#define IOC_ROPE_AO 0x10 /* Allow "Relaxed Ordering" */
+
+
/* AGP GART driver looks for this */
#define ZX1_SBA_IOMMU_COOKIE 0x0000badbadc0ffeeUL

@@ -1361,6 +1365,7 @@
#ifdef FULL_VALID_PDIR
unsigned long index;
#endif
+ unsigned int i;

/*
** Firmware programs the base and size of a "safe IOVA space"
@@ -1455,6 +1460,18 @@
/* Enable IOVA translation */
WRITE_REG(ioc->ibase | 1, ioc->ioc_hpa + IOC_IBASE); READ_REG(ioc->ioc_hpa + IOC_IBASE);
+
+ /* 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 tg3 on bcm5701.
+ */
+ for (i=0; i<(8*8); i+=8) {
+ unsigned long rope_config;
+ rope_config = READ_REG(ioc->ioc_hpa + IOC_ROPE0_CFG + i);
+ rope_config &= ~IOC_ROPE_AO;
+ WRITE_REG(rope_config, ioc->ioc_hpa + IOC_ROPE0_CFG + i);
+ }
}

static void __init