[U-Boot] [PATCH] tegra20: add back USE_PRIVATE_LIBGCC

[Allen Martin <amartin@nvidia.com>]

On Tue, Aug 07, 2012 at 10:53:00AM -0700, Lucas Stach wrote:
> Hi Allen,
> 
> And to answer Tom's question: the failure was that the real U-Boot would
> not come up after the SPL. All I could see was the one line printed by
> the SPL and nothing more.

I think I found the problem.  It's the following code from start.S:

ENTRY(cpu_init_crit)
       /*
        * Jump to board specific initialization...
        * The Mask ROM will have already initialized
        * basic memory. Go here to bump up clock rate and handle
        * wake up conditions.
        */
       mov     ip, lr                  @ persevere link reg across
       call
       bl      lowlevel_init           @ go setup pll,mux,memory
       mov     lr, ip                  @ restore link
       mov     pc, lr                  @ back to my caller
ENDPROC(cpu_init_crit)


The "ip" register is not preserved across function calls, and the
CodeSourcery compiler is using it in lowlevel_init or one of the
functions it calls.  This code was there before the SPL changes, but
wasn't being called because CONFIG_SKIP_LOWLEVEL_INIT was set, but now
it isn't.

Lucas, can you try the following change?  I tested it on seaboard with
CodeSourcery arm-2011.09-70-arm-none-linux-gnueabi and I'm able to
boot a kernel.

Tom if this works we probably want to get it into your pull request to
Albert.  CodeSourcery toolchain is probably used by a lot of people.

-Allen


diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
index 2506f27..02e47fa 100644
--- a/arch/arm/cpu/armv7/start.S
+++ b/arch/arm/cpu/armv7/start.S
@@ -152,7 +152,7 @@ reset:
        /* the mask ROM code should have PLL and others stable */
 #ifndef CONFIG_SKIP_LOWLEVEL_INIT
        bl      cpu_init_cp15
-       bl      cpu_init_crit
+       bl      lowlevel_init           @ go setup pll,mux,memory
 #endif

 /* Set stackpointer in internal RAM to call board_init_f */
@@ -339,29 +339,6 @@ ENTRY(cpu_init_cp15)
        mov     pc, lr                  @ back to my caller
 ENDPROC(cpu_init_cp15)

-#ifndef CONFIG_SKIP_LOWLEVEL_INIT
-/*************************************************************************
- *
- * CPU_init_critical registers
- *
- * setup important registers
- * setup memory timing
- *
- *************************************************************************/
-ENTRY(cpu_init_crit)
-       /*
-        * Jump to board specific initialization...
-        * The Mask ROM will have already initialized
-        * basic memory. Go here to bump up clock rate and handle
-        * wake up conditions.
-        */
-       mov     ip, lr                  @ persevere link reg across
-call
-       bl      lowlevel_init           @ go setup pll,mux,memory
-       mov     lr, ip                  @ restore link
-       mov     pc, lr                  @ back to my caller
-ENDPROC(cpu_init_crit)
-#endif
-
 #ifndef CONFIG_SPL_BUILD
 /*
  *************************************************************************


-- 
nvpublic