rk3288: Disable ramstage compression by default

The ramstage is loaded from romstage, so the LZMA scratchpad buffer used
to decompress it is part of the romstage BSS in SRAM. On RK3288, SRAM
cannot be cached which makes the decompression so slow that it's faster
to just load an uncompressed image from SPI. Disable ramstage
compression on this SoC to account for that.

[pg: implementation avoids restructuring all of Kconfig]

BRANCH=None
BUG=None
TEST=Built for Pinky and Falco, confirmed that the former didn't have
COMPRESS_RAMSTAGE in its .config and the latter still did. Measured a
speed-up of about 35ms on Pinky. (For some weird reason, the
decompression of the payload also takes way longer than on other
platforms, although not as long as the ramstage. I have no explanation
for that and can't really think of a good way to figure it out... maybe
the Cortex-A12 is just terrible at some operation that LZMA uses a lot?)

Change-Id: I9f67f7537696ec09496483b16b59a8b73f4cb11b
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/234192
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-on: http://review.coreboot.org/9792
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/Kconfig

@@ -135,9 +135,14 @@ config STATIC_OPTION_TABLE
 	  every boot.  Use this if you want the NVRAM configuration to
 	  never be modified from its default values.
 
+config UNCOMPRESSED_RAMSTAGE
+	bool
+	default n
+
 config COMPRESS_RAMSTAGE
 	bool "Compress ramstage with LZMA"
-	default y
+	default y if !UNCOMPRESSED_RAMSTAGE
+	default n
 	help
 	  Compress ramstage to save memory in the flash image. Note
 	  that decompression might slow down booting if the boot flash

src/soc/rockchip/rk3288/Kconfig

@@ -30,6 +30,7 @@ config SOC_ROCKCHIP_RK3288
 	select HAVE_UART_MEMORY_MAPPED
 	select HAVE_UART_SPECIAL
 	select BOOTBLOCK_CONSOLE
+	select UNCOMPRESSED_RAMSTAGE
 
 if SOC_ROCKCHIP_RK3288