[U-Boot] [PATCH] arm: re-implement proper ISB instruction for ARMv7-A

[Chen-Yu Tsai]

Hi,

On Thu, Jul 28, 2016 at 6:13 PM, Ziyuan Xu <xzy.xu at rock-chips.com> wrote:
> For ARMv7-A architecture, the valid ISB instruction is asm volatile("isb").
>
> This patch fixes the U-Boot was stuck in invalidate_dcache_all() before
> booting linux kernel, which occurred on rk3288-base development board
> such as evb-rk3288, rock2-rk3288. And something output via console like:
>
> => bootz 0x2000000
> 0x02000000
>    ramdisk start = 0x00000000, ramdisk end = 0x00000000
>    Continuing to boot without FDT
>    Initial value for argc=3
>    Final value for argc=3
>    using: ATAGS
>
>    Starting kernel ...
>
> Linux kernel exactly the same way(see arch/arm/include/asm/barrier.h).
>
> Signed-off-by: Ziyuan Xu <xzy.xu at rock-chips.com>
> ---
>
>  arch/arm/include/asm/system.h | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h
> index 2bdc0be..12d4ba0 100644
> --- a/arch/arm/include/asm/system.h
> +++ b/arch/arm/include/asm/system.h
> @@ -227,13 +227,15 @@ void __noreturn psci_system_reset(bool smc);
>   */
>  void save_boot_params_ret(void);
>
> -#define isb() __asm__ __volatile__ ("" : : : "memory")
> -
>  #define nop() __asm__ __volatile__("mov\tr0,r0\t@ nop\n\t");
>
>  #ifdef __ARM_ARCH_7A__
> +#define isb() __asm__ __volatile__ ("isb" : : : "memory")
> +
>  #define wfi() __asm__ __volatile__ ("wfi" : : : "memory")
>  #else
> +#define isb() __asm__ __volatile__ ("" : : : "memory")
> +
>  #define wfi()
>  #endif
>

arch/arm/include/asm/barriers.h already has a proper set of
ISB/DSB macros. Please consider using those instead.

You'll see they also support ARMv6's CP15 ISB/DSB.

Regards
ChenYu