[U-Boot] [PATCH] arm: ls1021atwr: optimize the deep sleep latency

[York Sun]

On 09/24/2015 12:52 AM, Tang Yuantian wrote:
> It will take more than 1s when wake up from deep sleep. Most of the
> time is spent on outputing information. This patch reduced the deep
> sleep latency by:
> 1. avoid outputing system informaton
> 2. remove flush cache after DDR restore
> 3. skip reloading second stage uboot binary when SD boot
> 
> Signed-off-by: Tang Yuantian <Yuantian.Tang at freescale.com>
> ---
>  board/freescale/common/arm_sleep.c      |  4 ----
>  board/freescale/ls1021atwr/ls1021atwr.c | 19 +++++++++++++++++--
>  2 files changed, 17 insertions(+), 6 deletions(-)
> 
> diff --git a/board/freescale/common/arm_sleep.c b/board/freescale/common/arm_sleep.c
> index 8e8b7fa..a498c65 100644
> --- a/board/freescale/common/arm_sleep.c
> +++ b/board/freescale/common/arm_sleep.c
> @@ -12,7 +12,6 @@
>  #include <asm/secure.h>
>  #endif
>  #include <asm/armv7.h>
> -#include <asm/cache.h>
>  
>  #if defined(CONFIG_LS102XA)
>  #include <asm/arch/immap_ls102xa.h>
> @@ -65,8 +64,6 @@ static void dp_ddr_restore(void)
>  
>  	for (i = 0; i < DDR_BUFF_LEN / 8; i++)
>  		*dst++ = *src++;
> -
> -	flush_dcache_all();
>  }
>  
>  static void dp_resume_prepare(void)
> @@ -74,7 +71,6 @@ static void dp_resume_prepare(void)
>  	dp_ddr_restore();
>  	board_sleep_prepare();
>  	armv7_init_nonsec();
> -	cleanup_before_linux();
>  #ifdef CONFIG_U_QE
>  	u_qe_resume();
>  #endif
> diff --git a/board/freescale/ls1021atwr/ls1021atwr.c b/board/freescale/ls1021atwr/ls1021atwr.c
> index 228dbf8..236376b 100644
> --- a/board/freescale/ls1021atwr/ls1021atwr.c
> +++ b/board/freescale/ls1021atwr/ls1021atwr.c
> @@ -521,8 +521,10 @@ int board_early_init_f(void)
>  	}
>  
>  #if defined(CONFIG_DEEP_SLEEP)
> -	if (is_warm_boot())
> -		fsl_dp_disable_console();
> +	if (is_warm_boot()) {
> +		timer_init();
> +		dram_init();
> +	}
>  #endif
>  
>  	return 0;
> @@ -531,6 +533,8 @@ int board_early_init_f(void)
>  #ifdef CONFIG_SPL_BUILD
>  void board_init_f(ulong dummy)
>  {
> +	void (*second_uboot)(void);
> +
>  	/* Clear the BSS */
>  	memset(__bss_start, 0, __bss_end - __bss_start);
>  
> @@ -551,6 +555,17 @@ void board_init_f(ulong dummy)
>  	enable_devices_ns_access(&ns_dev[7], 1);
>  #endif
>  
> +	/*
> +	 * if it is woken up from deep sleep, then jump to second
> +	 * stage uboot and continue executing without recopying
> +	 * it from SD since it has already been reserved in memeory
> +	 * in last boot.
> +	 */
> +	if (is_warm_boot()) {
> +		second_uboot = (void (*)(void))CONFIG_SYS_TEXT_BASE;
> +		second_uboot();
> +	}
> +
>  	board_init_r(NULL, 0);
>  }
>  #endif
> 

Yuantian,

Please explain more why the second stage u-boot is reserved? Wouldn't Linux
overwrite the memory?

York