powerpc: Use 64k io pages when we never see an HEA
authorAlexander Graf <agraf@suse.de>
Tue, 1 Apr 2014 13:46:05 +0000 (15:46 +0200)
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>
Wed, 30 Apr 2014 22:25:16 +0000 (08:25 +1000)
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.

[ Updated the test to also lift the restriction on arch 2.07
  (Power 8) which cannot have an HEA
 -- BenH ]

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
foo

arch/powerpc/mm/hash_utils_64.c

index d766d6ee33fe6889e5a96b3898f8c47b0050fc14..12f1a397f5023bf339c93cc9cac78e1ac5880ca4 100644 (file)
@@ -445,6 +445,24 @@ static void mmu_psize_set_default_penc(void)
                        mmu_psize_defs[bpsize].penc[apsize] = -1;
 }
 
+#ifdef CONFIG_PPC_64K_PAGES
+
+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 !cpu_has_feature(CPU_FTR_ARCH_207S);
+#else
+       return false;
+#endif
+}
+
+#endif /* #ifdef CONFIG_PPC_64K_PAGES */
+
 static void __init htab_init_page_sizes(void)
 {
        int rc;
@@ -499,10 +517,11 @@ 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;