linux-kernel - Re: [PATCH 1/3] ARM: at91: flush the L2 cache before entering cpu idle

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 6 Jan 2017 10:05:17 +0100
From:   Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:     Wenyou Yang <wenyou.yang@...el.com>
Cc:     Russell King <linux@....linux.org.uk>,
        Nicolas Ferre <nicolas.ferre@...el.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-kernel@...r.kernel.org,
        Wenyou Yang <wenyou.yang@...rochip.com>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/3] ARM: at91: flush the L2 cache before entering cpu
 idle

Hi,

On 06/01/2017 at 14:59:45 +0800, Wenyou Yang wrote :
> For the SoCs such as SAMA5D2 and SAMA5D4 which have L2 cache,
> flush the L2 cache first before entering the cpu idle.
> 
> Signed-off-by: Wenyou Yang <wenyou.yang@...el.com>
> ---
> 
>  arch/arm/mach-at91/pm.c       | 19 +++++++++++++++++++
>  drivers/memory/atmel-sdramc.c |  1 +
>  2 files changed, 20 insertions(+)
> 
> diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c
> index b4332b727e9c..1a60dede1a01 100644
> --- a/arch/arm/mach-at91/pm.c
> +++ b/arch/arm/mach-at91/pm.c
> @@ -289,6 +289,24 @@ static void at91_ddr_standby(void)
>  		at91_ramc_write(1, AT91_DDRSDRC_LPR, saved_lpr1);
>  }
>  
> +static void at91_ddr_cache_standby(void)
> +{
> +	u32 saved_lpr;
> +
> +	flush_cache_all();
> +	outer_disable();
> +
> +	saved_lpr = at91_ramc_read(0, AT91_DDRSDRC_LPR);
> +	at91_ramc_write(0, AT91_DDRSDRC_LPR, (saved_lpr &
> +			(~AT91_DDRSDRC_LPCB)) | AT91_DDRSDRC_LPCB_SELF_REFRESH);
> +
> +	cpu_do_idle();
> +
> +	at91_ramc_write(0, AT91_DDRSDRC_LPR, saved_lpr);
> +
> +	outer_resume();
> +}
> +

Seems good to me. Did you measure the added latency on sama5d3 if you
add the cache operations in at91_ddr_standby instead of having a new
function?


-- 
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com