[PATCH v2] ARM: imx: Enable MMU and dcache very early on i.MX8M

[Peng Fan]

> Subject: [PATCH v2] ARM: imx: Enable MMU and dcache very early on
> i.MX8M
> 
> Enable MMU and caches very early on in the boot process on i.MX8M
> in U-Boot proper. This allows board_init_f to run with icache and
> dcache enabled, which saves some 700 milliseconds of boot time on
> i.MX8M Plus based device.
> 
> The 'bootstage report' output is below:
> 
> Before:
> ```
> Timer summary in microseconds (8 records):
>        Mark    Elapsed  Stage
>           0          0  reset
>     961,363    961,363  board_init_f
>   1,818,874    857,511  board_init_r
>   1,921,474    102,600  eth_common_init
>   2,013,702     92,228  eth_initialize
>   2,015,238      1,536  main_loop
> 
> Accumulated time:
>                 32,775  dm_r
>                289,165  dm_f
> ```
> 
> After:
> ```
> Timer summary in microseconds (8 records):
>        Mark    Elapsed  Stage
>           0          0  reset
>     989,466    989,466  board_init_f
>   1,179,100    189,634  board_init_r
>   1,281,456    102,356  eth_common_init
>   1,373,857     92,401  eth_initialize
>   1,375,396      1,539  main_loop
> 
> Accumulated time:
>                 12,630  dm_f
>                 32,635  dm_r
> ```
> 
> Signed-off-by: Marek Vasut <marex at denx.de>
> ---

Reviewed-by: Peng Fan <peng.fan at nxp.com>