From: Amit Kucheria <amit.kucheria@verdurent.com>
Date: Wed, 1 Sep 2010 19:49:13 +0000 (+0300)
Subject: ARM: mxc: turn off HWCAP_NEON for older versions of imx51 silicon
X-Git-Tag: firefly_0821_release~7613^2~3645^2~7^2~8^2~4
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=33d7c5c1c808ea47d85630ac2dd98490d7df0ff4;p=firefly-linux-kernel-4.4.55.git

ARM: mxc: turn off HWCAP_NEON for older versions of imx51 silicon

Versions of silicon older than TO3 have broken NEON implementation. Turn off
NEON in such cases.

Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org>
Tested-by: Dave Martin <dave.martin@linaro.org>
Tested-by: Jason Hui <jason.hui@linaro.org>
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
---

diff --git a/arch/arm/mach-mx5/cpu.c b/arch/arm/mach-mx5/cpu.c
index 2d37785e3857..eaacb6e9b5d0 100644
--- a/arch/arm/mach-mx5/cpu.c
+++ b/arch/arm/mach-mx5/cpu.c
@@ -70,6 +70,25 @@ int mx51_revision(void)
 }
 EXPORT_SYMBOL(mx51_revision);
 
+#ifdef CONFIG_NEON
+
+/*
+ * All versions of the silicon before Rev. 3 have broken NEON implementations.
+ * Dependent on link order - so the assumption is that vfp_init is called
+ * before us.
+ */
+static int __init mx51_neon_fixup(void)
+{
+	if (mx51_revision() < MX51_CHIP_REV_3_0 && (elf_hwcap & HWCAP_NEON)) {
+		elf_hwcap &= ~HWCAP_NEON;
+		pr_info("Turning off NEON support, detected broken NEON implementation\n");
+	}
+	return 0;
+}
+
+late_initcall(mx51_neon_fixup);
+#endif
+
 static int __init post_cpu_init(void)
 {
 	unsigned int reg;