Merge patch series "Move framebuffer reservation for SPL to RAM end"

Devarsh Thakkar <devarsht@ti.com> says:

Move video memory reservation for SPL at end of RAM so that it does
not interefere with reservations for next stage so that the next stage
need not have holes in between for passed regions and instead it can
maintain continuity in reservations.

Also catch the bloblist before starting reservations to avoid the same
problem.

While at it, also fill missing fields in video handoff struct before
passing it to next stage.

This is as per discussions at :
For moving SPL framebuffer reservation at end of RAM:

https://lore.kernel.org/all/CAPnjgZ3xSoe_G3yrqwuAvoiVjUfZ+YQgkOR0ZTVXGT9VK8TwJg@mail.gmail.com/

For filling missing video handoff fields :
https://lore.kernel.org/all/CAPnjgZ1Hs0rNf0JDirp6YPsOQ5=QqQSP9g9qRwLoOASUV8a4cw@mail.gmail.com/

1 files changed, 37 insertions, 0 deletions

diff --git a/doc/develop/spl.rst b/doc/develop/spl.rst
index 76e87f07c72..0a3e572310a 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)
 
 Adding SPL-specific code
 ------------------------
@@ -164,3 +173,31 @@ 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 needs to be reserved in RAM during SPL stage with the requirement that
+the SPL reserved memory remains preserved across further boot stages too
+then it needs to be reserved mandatorily starting from end of RAM. This is to
+ensure that further stages can simply skip this region before carrying out
+further reservations or updating the relocation address.
+
+Also out of these regions which are to be preserved across further stages of
+boot, video framebuffer memory region must be reserved first starting from
+end of RAM for which helper function spl_reserve_video_from_ram_top is provided
+which makes sure that video memory is placed at top of reservation area with
+further reservations below it.
+
+The corresponding information of reservation for those regions can be passed to
+further boot stages 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.
+
+The further boot stages need to parse each of the bloblist passed from SPL stage
+starting from video bloblist and skip this whole SPL reserved memory area from
+end of RAM as per the bloblists received, before carrying out further
+reservations or updating the relocation address. For e.g, U-boot proper uses
+function "setup_relocaddr_from_bloblist" to parse the bloblists passed from
+previous stage and skip the memory reserved from previous stage accordingly.