On Wed, 18 Feb 2015 15:16:28 +0530 Akshay Saraswat akshay.s@samsung.com wrote:
This patch adds workaround for the ARM errata 799270 which says "If the L2 cache logic clock is stopped because of L2 inactivity, setting or clearing the ACTLR.SMP bit might not be effective. The bit is modified in the ACTLR, meaning a read of the register returns the updated value. However the logic that uses that bit retains the previous value."
Signed-off-by: Kimoon Kim kimoon.kim@samsung.com Signed-off-by: Akshay Saraswat akshay.s@samsung.com Reviewed-by: Simon Glass sjg@chromium.org Tested-by: Simon Glass sjg@chromium.org
Changes since v2:
- No change.
Changes since v1:
- Added Reviewed-by & Tested-by.
arch/arm/cpu/armv7/exynos/lowlevel_init.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)
diff --git a/arch/arm/cpu/armv7/exynos/lowlevel_init.c b/arch/arm/cpu/armv7/exynos/lowlevel_init.c index 7335a1e..bbcae4c 100644 --- a/arch/arm/cpu/armv7/exynos/lowlevel_init.c +++ b/arch/arm/cpu/armv7/exynos/lowlevel_init.c @@ -46,6 +46,28 @@ enum {
#ifdef CONFIG_EXYNOS5420 /*
- Ensure that the L2 logic has been used within the previous 256 cycles
- before modifying the ACTLR.SMP bit. This is required during boot before
- MMU has been enabled, or during a specified reset or power down sequence.
- */
+void enable_smp(void) +{
- uint32_t temp, val;
- /* Enable SMP mode */
- mrc_auxr(temp);
- temp |= (1 << 6);
- /* Dummy read to assure L2 access */
- val = readl(EXYNOS5420_INFORM_BASE);
- val &= 0;
- temp |= val;
Wouldn't the compiler happily optimize out some parts of this code?
- mcr_auxr(temp);
- dsb();
- isb();
+}
This looks like a general purpose ARM Cortex-A15 workaround too. Except that the EXYNOS5420_INFORM_BASE address is Exynos specific.