[U-Boot] [PATCH 1/2 V2] arm926: Flush the data cache before disabling it.

[Christian Riesch]

Hi Sughosh,

On Tue, Jan 10, 2012 at 7:12 PM, Sughosh Ganu <urwithsughosh at gmail.com> wrote:
> The current implementation invalidates the cache instead of flushing
> it. This causes problems on platforms where the spl/u-boot is already
> loaded to the RAM, with caches enabled by a first stage bootloader.
>
> The V bit of the cp15's control register c1 is set to the value of
> VINITHI on reset. Do not clear this bit by default, as there are SOC's
> with no valid memory region at 0x0.
>
> Signed-off-by: Sughosh Ganu <urwithsughosh at gmail.com>
> Cc: Albert Aribaud <albert.u.boot at aribaud.net>
> ---
>
> Changes since V1
> * Added arm926 keyword to the subject line
> * Removed the superfluous setting of r0.
> * Fixed the comment to reflect the fact that V is not being cleared

I did a few tests of this patch with the da850evm (on an AM1808
experimenter's kit) and the calimain (on our custom board)
configurations.

I used u-boot from git://git.denx.de/u-boot-ti.git master, head is
14023683951b9a2bd277e999b0798b4917aca5d5. On top of this I applied
these three patches:

[U-Boot,1/2,V2] arm926: Flush the data cache before disabling it.
http://patchwork.ozlabs.org/patch/135275/

[U-Boot,2/2,V4] Changes to move hawkboard to the new spl infrastructure
http://patchwork.ozlabs.org/patch/135433/

[U-Boot,v2] arm, davinci: Add support for the Calimain board from
OMICRON electronics
http://patchwork.ozlabs.org/patch/135593/

First I compiled for the da850evm.
make mrproper
make da850evm_config
make -j3 -s u-boot.ais

I flashed the resulting u-boot.ais to the SPI flash of the AM1808
experimenter's kit:
mono dvflashutils/OMAP-L138/GNU/sfh_OMAP-L138.exe -targetType AM1808
-flashType SPI_MEM -p /dev/ttyUSB0 -flash_noubl ../u-boot/u-boot.ais
And tried to boot -> SUCCESS

I also tried the TI way (using the ubl):
mono dvflashutils/OMAP-L138/GNU/sfh_OMAP-L138.exe -targetType AM1808
-flashType SPI_MEM -p /dev/ttyUSB0 -flash
dvflashutils/OMAP-L138/GNU/ubl/ubl_AM1808_SPI_MEM.bin
../u-boot/u-boot.bin
And tried to boot -> SUCCESS

Countercheck: I reverted patch "[U-Boot,1/2,V2] arm926: Flush the data
cache before disabling it." and rebuilt
git revert HEAD~2
make mrproper
make da850evm_config
make -j3 -s u-boot.ais

Again I tried with ubl and without -> both worked -> SUCCESS

Since you state that problems arise with the AIS scripts I also did a
test loading u-boot with an AIS.

This is my da850evm.ini
[General]
busWidth=8
BootMode=SPIMASTER
crcCheckType=NO_CRC
[PLLANDCLOCKCONFIG]
PLL0CFG0 = 0x00180001
PLL0CFG1 = 0x00000205
PERIPHCLKCFG = 0x00000002
[EMIF3DDR]
PLL1CFG0 = 0x15010001
PLL1CFG1 = 0x00000002
DDRPHYC1R = 0x000000C4
SDCR = 0x0A034622
SDTIMR = 0x184929C8
SDTIMR2 = 0xB80FC700
SDRCR = 0x00000406
CLK2XSRC = 0x00000000
[INPUTFILE]
FILENAME=u-boot.bin
LOADADDRESS=0xC1080000
ENTRYPOINTADDRESS=0xC1080000

I run
mono dvflashutils/OMAP-L138/GNU/AISUtils/HexAIS_OMAP-L138.exe -ini
da850evm.ini -o u-boot.ais
program to flash and run -> SUCCESS

I undo the revert
git reset --hard HEAD^
and rebuild
make mrproper
make da850evm_config
make -j3 -s u-boot.ais
program and run -> SUCCESS

Similar tests with the calimain board were also successful.

Since all my tests were successful I wonder what issues did you have
with the cache? Can you describe the problems you had? I think the
difference is that you are booting from NAND and have an OMAP-L138,
whereas I boot from SPI (on the da850evm) or from NOR (on calimain)
and have an AM1808 on both boards, right?

Regards, Christian