[PATCH] powerpc: Use 64k io pages when we never see an HEA

Alexander Graf agraf at suse.de
Wed Apr 2 00:46:05 EST 2014


When we never get around to seeing an HEA ethernet adapter, there's
no point in restricting ourselves to 4k IO page size.

This speeds up IO maps when CONFIG_IBMEBUS is disabled.

Signed-off-by: Alexander Graf <agraf at suse.de>
---
 arch/powerpc/mm/hash_utils_64.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index d766d6e..c0ef976 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -445,6 +445,20 @@ static void mmu_psize_set_default_penc(void)
 			mmu_psize_defs[bpsize].penc[apsize] = -1;
 }
 
+static bool might_have_hea(void)
+{
+	/*
+	 * The HEA ethernet adapter requires awareness of the
+	 * GX bus. Without that awareness we can easily assume
+	 * we will never see an HEA ethernet device.
+	 */
+#ifdef CONFIG_IBMEBUS
+	return true;
+#else
+	return false;
+#endif
+}
+
 static void __init htab_init_page_sizes(void)
 {
 	int rc;
@@ -499,10 +513,11 @@ static void __init htab_init_page_sizes(void)
 			mmu_linear_psize = MMU_PAGE_64K;
 		if (mmu_has_feature(MMU_FTR_CI_LARGE_PAGE)) {
 			/*
-			 * Don't use 64k pages for ioremap on pSeries, since
-			 * that would stop us accessing the HEA ethernet.
+			 * When running on pSeries using 64k pages for ioremap
+			 * would stop us accessing the HEA ethernet. So if we
+			 * have the chance of ever seeing one, stay at 4k.
 			 */
-			if (!machine_is(pseries))
+			if (!might_have_hea() || !machine_is(pseries))
 				mmu_io_psize = MMU_PAGE_64K;
 		} else
 			mmu_ci_restrictions = 1;
-- 
1.8.1.4



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