[U-Boot] Cache alignment warnings on Tegra (ARM)

[Stephen Warren]

On 09/12/2012 10:19 AM, Tom Warren wrote:
> Folks,
> 
> Stephen Warren has posted an internal bug regarding the cache
> alignment 'warnings' seen on Tegra20 boards when accessing MMC. Here's
> the gist:
> 
> Executing "mmc dev 0" still yields cache warnings:
> 
> Tegra20 (Harmony) # mmc dev 0
> ERROR: v7_dcache_inval_range- stop address is not aligned- 0x3fb69908
> mmc0 is current device
...
> There have been patches in the past (IIRC) that have tried to ensure
> all callers (FS, MMC driver, USB driver, etc.) force their buffers to
> the appropriate alignment, but I don't know that we can ever correct
> every instance, now or in the future.
> 
> Can we start a discussion about what we can do about this warning?
> Adding an appropriate #ifdef (CONFIG_SYS_NO_CACHE_ALIGNMENT_WARNINGS,
> etc.) where Stephen put his #if 0's would be one approach, or changing
> the printf() to a debug(), perhaps. As far as I can tell, these
> alignment 'errors' don't seem to produce bad data in the transfer.

I don't think simply turning off the warning is the correct approach; I
believe they represent real problems that can in fact cause data
corruption. I don't believe we have any choice other than to fully solve
the root-cause.