On Thu, Dec 15, 2016 at 04:55:44PM +0000, york sun wrote:
On 12/14/2016 10:22 PM, Zhiqiang Hou wrote:
From: Mingkai Hu mingkai.hu@nxp.com
For A53, data coherency is enabled only when the CPUECTLR.SMPEN bit is set. The SMPEN bit should be set before enabling the data cache. If not enabled, the cache is not coherent with other cores and data corruption could occur.
For A57/A72, SMPEN bit enables the processor to receive instruction cache and TLB maintenance operations broadcast from other processors in the cluster. This bit should be set before enabling the caches and MMU, or performing any cache and TLB maintenance operations.
Signed-off-by: Mingkai Hu mingkai.hu@nxp.com Signed-off-by: Gong Qianyu Qianyu.Gong@nxp.com Signed-off-by: Mateusz Kulikowski mateusz.kulikowski@gmail.com Signed-off-by: Hou Zhiqiang Zhiqiang.Hou@nxp.com
arch/arm/cpu/armv8/Kconfig | 12 ++++++++++++ arch/arm/cpu/armv8/start.S | 11 +++++++++++ 2 files changed, 23 insertions(+)
diff --git a/arch/arm/cpu/armv8/Kconfig b/arch/arm/cpu/armv8/Kconfig index 965a8d1..ce749f2 100644 --- a/arch/arm/cpu/armv8/Kconfig +++ b/arch/arm/cpu/armv8/Kconfig @@ -3,6 +3,18 @@ if ARM64 config ARMV8_MULTIENTRY bool "Enable multiple CPUs to enter into U-Boot"
+config ARMV8_SET_SMPEN
bool "Enable data coherency with other cores in cluster"helpCortex A53/57/72 cores require CPUECTLR_EL1.SMPEN set evenfor single core systems. Unfortunately write access to thisregister may be controlled by EL3/EL2 firmware. To be moreprecise, by default (if there is EL2/EL3 firmware running)this register is RO for NS EL1.This switch can be used to avoid writing to CPUECTLR_EL1,it can be safely enabled when El2/EL3 initialized SMPEN bitor when CPU implementation doesn't include that register.config ARMV8_SPIN_TABLE bool "Support spin-table enable method" depends on ARMV8_MULTIENTRY && OF_LIBFDT diff --git a/arch/arm/cpu/armv8/start.S b/arch/arm/cpu/armv8/start.S index 4f5f6d8..5308702 100644 --- a/arch/arm/cpu/armv8/start.S +++ b/arch/arm/cpu/armv8/start.S @@ -86,6 +86,17 @@ save_boot_params_ret: msr cpacr_el1, x0 /* Enable FP/SIMD */ 0:
- /*
* Enalbe SMPEN bit for coherency.* This register is not architectural but at the moment* this bit should be set for A53/A57/A72.*/+#ifdef CONFIG_ARMV8_SET_SMPEN
- mrs x0, S3_1_c15_c2_1 /* cpuactlr_el1 */
- orr x0, x0, #0x40
- msr S3_1_c15_c2_1, x0
+#endif
- /* Apply ARM core specific erratas */ bl apply_core_errata
Would it be a good idea to detect the core and apply this setting at run time, instead of using Kconfig option? Check the macro branch_if_a53_core, branch_if_a57_core for example.
I think we need to look back at the discussion from the last time we made a change around here, and make sure to fully understand what platforms do and do not need / want to touch that. See d73718f3236c520a92efa401084c658e6cc067f3 and then 3a592a1349ac3961b0f4f2db0a8d9f128225d897.