On 1/4/2013 5:54 PM, Fabio Estevam wrote:
From: Fabio Estevam fabio.estevam@freescale.com
Add workaround for the following ARM errata: 743622 and 751472.
The motivation for this change is the following kernel commit 62e4d357a (ARM: 7609/1: disable errata work-arounds which access secure registers), which removes the errata from multiplatform kernel.
Since imx has been converted to multiplatform in the kernel, we need to apply such workaround into the bootloader.
Workaround code has been taken from arch/arm/mm/proc-v7.S from 3.7.1 kernel.
Signed-off-by: Fabio Estevam fabio.estevam@freescale.com
Following patch has been proposed into arm kernel mailing list: http://www.spinics.net/lists/arm-kernel/msg214840.html
Changes since v1:
Use the same style of the erratum in arch/arm/cpu/armv7/mx5/lowlevel_init.S.
arch/arm/cpu/armv7/mx6/lowlevel_init.S | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/arch/arm/cpu/armv7/mx6/lowlevel_init.S b/arch/arm/cpu/armv7/mx6/lowlevel_init.S index acadef2..ae8141d 100644 --- a/arch/arm/cpu/armv7/mx6/lowlevel_init.S +++ b/arch/arm/cpu/armv7/mx6/lowlevel_init.S @@ -20,6 +20,16 @@
#include <linux/linkage.h>
+.macro init_arm_errata
- mrc 15, 0, r1, c1, c0, 1 /* read diagnostic register */
i.MX 6Quad_6Dual Errata (Rev 0) TO1.2.pdf says this should be
mrc 15, 0, r1, c15, c0, 1
Since it also says "undocumented Diagnostic Control register" and "c1, c0, 1" is "Auxiliary Control Register" I think c15 is right.
Besides, you had C15 in rev 1.
- /* ARM erratum ID #743622 */
- orr r1, r1, #(1 << 6) /* set bit #6 */
- /* ARM erratum ID #751472 */
- orr r1, r1, #(1 << 11) /* set bit #11 */
- mcr 15, 0, r1, c1, c0, 1 /* write diagnostic register */
mcr 15, 0, r1, c15, c0, 1
+.endm
- ENTRY(lowlevel_init)
- init_arm_errata mov pc, lr ENDPROC(lowlevel_init)