How to enable cache in U-boot

x10

Hi, All

There are always a warning message on u-boot start:

U-Boot 2013.10 (Jan 06 2014 - 14:10:46)

I2C: ready
DRAM: 256 MiB
WARNING: Caches not enabled
NAND: 256 MiB

I just implement splash bmp display which is slow, so that I believe the cache is NOT enabled really. Thanks for any suggestion to fix the issue.

Another issue of speed is nand read which take quite a few seconds to load zImage into DDR3. Are there any patch available to speed up nand reading in em335x_evm? Thanks.

Cheng Shi

emtronix

over 11 years ago

0 Steve Kipisz over 11 years ago

TI__Genius 15510 points

I do not have access to my u-boot sources, but I think if you add

#define CONFIG_CMD_CACHE

to your am335x_evm.h file and re-build u-boot, you should have the commands to enable cache. I think the command will be dcache on.

Steve K.

0 x10 over 11 years ago in reply to Steve Kipisz

Intellectual 765 points

Thanks for quick reply Steve. I'll try it soon.

Cheng Shi

0 x10 over 11 years ago in reply to x10

Intellectual 765 points

Hi, Steve

Thanks for your hit. It's required to implement function enable_caches() to enable dcache. With dcache on, speed of splash is quick indeed.

Cheng Shi

0 John Murphy1 over 11 years ago in reply to x10

Expert 1210 points

By default, in the am335x u-boot supplied in the SDK (ti-sdk-am335x-evm-06.00.00.00/board-support/u-boot-2013.01.01-psp06.00.00.00), the instruction cache is enabled and the data cache is disabled. This is due to DMA coherency issues somewhere in the drivers (see the u-boot git history). I'm not sure where the problem lies.

I found that for my configuration (NAND), I could enable dcache in u-boot (but not in u-boot SPL!), and it did speed things up.

0 x10 over 11 years ago in reply to John Murphy1

Intellectual 765 points

What I did is to add following code:

#ifndef CONFIG_SYS_DCACHE_OFF
void enable_caches(void)
{
/* Enable D-cache. I-cache is already enabled in start.S */
dcache_enable();
}
#endif /* CONFIG_SYS_DCACHE_OFF */

enable_caches() will be called at beginning of board_init_r in u-boot-2013.10, which speed splash indeed.

0 Brian Tremaine over 10 years ago in reply to x10

Prodigy 200 points

For a Beaglebone Black do I add this code to arch/arm/lib/cache.c ?? (enable_caches is now a stub)

Thank you very much for this!! I've been searching for 3 days on how to enable the cache!

0 x10 over 10 years ago in reply to Brian Tremaine

Intellectual 765 points

I just put the following code:

#ifndef CONFIG_SYS_DCACHE_OFF
void enable_caches(void)
{
/* Enable D-cache. I-cache is already enabled in start.S */
dcache_enable();
}
#endif

in ../board/ti/am335x/board.c

Hope it's helpful.

Cheng Shi

Processors

Processors forum

How to enable cache in U-boot