[PATCH v2 6/6] doc: spl: Add info regarding memory reservation and missing Kconfigs

[Simon Glass]

Hi Devarsh,

On Fri, 10 Nov 2023 at 08:29, Devarsh Thakkar <devarsht at ti.com> wrote:
>
> Add information regarding memory reservation scheme in SPL
> and details regarding scheme which need to be followed while reserving
> those areas which need to be preserved across bootstages.
>
> Also add missing CONFIG_SPL Kconfigs and new ones which were added
> recently.
>
> Signed-off-by: Devarsh Thakkar <devarsht at ti.com>
> ---
> V1->V3 : No change
> ---
>  doc/develop/spl.rst | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
>
> diff --git a/doc/develop/spl.rst b/doc/develop/spl.rst
> index 76e87f07c7..fc570589eb 100644
> --- a/doc/develop/spl.rst
> +++ b/doc/develop/spl.rst
> @@ -65,6 +65,15 @@ CONFIG_SPL_NAND_LOAD (drivers/mtd/nand/raw/nand_spl_load.o)
>  CONFIG_SPL_SPI_LOAD (drivers/mtd/spi/spi_spl_load.o)
>  CONFIG_SPL_RAM_DEVICE (common/spl/spl.c)
>  CONFIG_SPL_WATCHDOG (drivers/watchdog/libwatchdog.o)
> +CONFIG_SPL_SYSCON (drivers/core/syscon-uclass.o)
> +CONFIG_SPL_GZIP (lib/gzip.o)
> +CONFIG_SPL_VIDEO (drivers/video/video-uclass.o drivers/video/vidconsole-uclass.o)
> +CONFIG_SPL_SPLASH_SCREEN (common/splash.o)
> +CONFIG_SPL_SPLASH_SOURCE (common/splash_source.o)
> +CONFIG_SPL_GPIO (drivers/gpio)
> +CONFIG_SPL_DM_GPIO (drivers/gpio/gpio-uclass.o)
> +CONFIG_SPL_BMP (drivers/video/bmp.o)
> +CONFIG_SPL_BLOBLIST (common/bloblist.o)

Did you intend to add the above? If so, please put it in its own patch.

>
>  Adding SPL-specific code
>  ------------------------
> @@ -164,3 +173,16 @@ cflow will spit out a number of warnings as it does not parse
>  the config files and picks functions based on #ifdef.  Parsing the '.i'
>  files instead introduces another set of headaches.  These warnings are
>  not usually important to understanding the flow, however.
> +
> +
> +Reserving memory in SPL
> +-----------------------
> +
> +If memory need to be reserved in RAM during SPL stage so that area won't get touched
> +by SPL and/or u-boot, it need to be reserved starting from end of RAM.

U-Boot (please avoid using any other spelling in docs and comments;
please fix globally)

> +
> +Also the regions which are to be preserved across further stages of boot need to be reserved first starting from
> +framebuffer memory which must be reserved from end of RAM for which helper function spl_reserve_video_from_ram_top is provided.

Worth mentioning that framebuffer being reserved first means it is at
the top of the reservation area with everything else reserved below
it?

> +
> +The corresponding information of reservation for those regions can be passed to further stages of boot using a bloblist.
> +For e.g. the information for framebuffer area reserved by SPL can be passed onto u-boot using BLOBLISTT_U_BOOT_VIDEO.

Can you please wrap to 80 cols?

> --
> 2.34.1
>

Regards,
Simon