From: Ralf Baechle <ralf@linux-mips.org>
Date: Thu, 20 Oct 2005 21:55:26 +0000 (+0100)
Subject: Hack to resolve longstanding prefetch issue
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=e5adb8770e12169a6595a3ad5682541441bd1052;p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git

Hack to resolve longstanding prefetch issue

Prefetching may be fatal on some systems if we're prefetching beyond the
end of memory on some systems.  It's also a seriously bad idea on non
dma-coherent systems.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
---

diff --git a/arch/mips/lib/memcpy.S b/arch/mips/lib/memcpy.S
index a78865f7654..7f9aafa4d80 100644
--- a/arch/mips/lib/memcpy.S
+++ b/arch/mips/lib/memcpy.S
@@ -13,6 +13,21 @@
  * Mnemonic names for arguments to memcpy/__copy_user
  */
 #include <linux/config.h>
+
+/*
+ * Hack to resolve longstanding prefetch issue
+ *
+ * Prefetching may be fatal on some systems if we're prefetching beyond the
+ * end of memory on some systems.  It's also a seriously bad idea on non
+ * dma-coherent systems.
+ */
+#if !defined(CONFIG_DMA_COHERENT) || !defined(CONFIG_DMA_IP27)
+#undef CONFIG_CPU_HAS_PREFETCH
+#endif
+#ifdef CONFIG_MIPS_MALTA
+#undef CONFIG_CPU_HAS_PREFETCH
+#endif
+
 #include <asm/asm.h>
 #include <asm/asm-offsets.h>
 #include <asm/regdef.h>