xtensa: minimize use of PLATFORM_DEFAULT_MEM_{ADDR,SIZE}

Now that the kernel load address and KSEG physical base address have
their own Kconfig symbols PLATFORM_DEFAULT_MEM seems redundant. It makes
little sense to use it in MMU configurations instead of KSEG_PADDR.
In noMMU configurations there's no explicit KSEG, so it's still useful
for the early cache initialization and definition of ARCH_PFN_OFFSET,
which affects mem_map size.

- limit it to noMMU; MMU variants have XCHAL_KSEG_PADDR and
  XCHAL_KSEG_SIZE;
- don't use it to define TASK_SIZE or MAX_LOW_PFN: first doesn't make
  any difference in noMMU, second is meaningless as there's no high
  memory;
- don't add default physical memory region: memory layout should come
  from the DT, bootloader tags, or memmap= command line parameter.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

1 files changed, 7 insertions, 11 deletions

diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index 9b1f8c3c..7a4c77b 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -394,7 +394,7 @@ config XTENSA_PLATFORM_XT2000
 config XTENSA_PLATFORM_XTFPGA
 	bool "XTFPGA"
 	select ETHOC if ETHERNET
-	select PLATFORM_WANT_DEFAULT_MEM
+	select PLATFORM_WANT_DEFAULT_MEM if !MMU
 	select SERIAL_CONSOLE
 	select XTENSA_CALIBRATE_CCOUNT
 	help
@@ -502,11 +502,9 @@ config DEFAULT_MEM_START
 	default 0x00000000 if MMU
 	default 0x60000000 if !MMU
 	help
-	  This is a fallback start address of the default memory area, it is
-	  used when no physical memory size is passed through DTB or through
-	  boot parameter from bootloader.
-
-	  It's also used for TASK_SIZE calculation in noMMU configuration.
+	  This is the base address of the default memory area.
+	  Default memory area has platform-specific meaning, it may be used
+	  for e.g. early cache initialization.
 
 	  If unsure, leave the default value here.
 
@@ -515,11 +513,9 @@ config DEFAULT_MEM_SIZE
 	depends on PLATFORM_WANT_DEFAULT_MEM
 	default 0x04000000
 	help
-	  This is a fallback size of the default memory area, it is used when
-	  no physical memory size is passed through DTB or through boot
-	  parameter from bootloader.
-
-	  It's also used for TASK_SIZE calculation in noMMU configuration.
+	  This is the size of the default memory area.
+	  Default memory area has platform-specific meaning, it may be used
+	  for e.g. early cache initialization.
 
 	  If unsure, leave the default value here.