[PATCH master v2] ARM: i.MX7: enable caches when booted over USB

[Sascha Hauer]

On Mon, Oct 10, 2022 at 08:34:30AM +0200, Ahmad Fatoum wrote:
> BootROM on the i.MX7 doesn't set the SMP bit when booted
> over serial download. This leads to vastly worse performance
> when doing memory-heavy operations in a USB-booted system,
> as the caches are not utilized. Example running md5sum over
> a 25M image in ramfs:
> 
>   without patch: 10796ms
>   with    patch: 457ms
> 
> This issue isn't unique to the i.MX7, but exists for the i.MX6UL as
> well, which also has the Cortex-A7 as CPU. Like with
> imx6ul_cpu_lowlevel_init(), adapt imx7_cpu_lowlevel_init() to avoid this
> slow down.
> 
> Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
> Signed-off-by: Johannes Zink <j.zink at pengutronix.de>
> ---
> v1 -> v2:
>   - don't drop arm arm_cpu_lowlevel_init as cortex_a7_lowlevel_init
>     does not call it (Marco)
> ---
>  arch/arm/mach-imx/cpu_init.c | 1 +
>  1 file changed, 1 insertion(+)

Applied, thanks

Sascha

> 
> diff --git a/arch/arm/mach-imx/cpu_init.c b/arch/arm/mach-imx/cpu_init.c
> index ea3621541979..3f16ca70ce26 100644
> --- a/arch/arm/mach-imx/cpu_init.c
> +++ b/arch/arm/mach-imx/cpu_init.c
> @@ -49,6 +49,7 @@ void imx6ul_cpu_lowlevel_init(void)
>  
>  void imx7_cpu_lowlevel_init(void)
>  {
> +	cortex_a7_lowlevel_init();
>  	arm_cpu_lowlevel_init();
>  	imx_cpu_timer_init(IOMEM(MX7_SYSCNT_CTRL_BASE_ADDR));
>  }
> -- 
> 2.30.2
> 
> 
> 

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |