Dear Thierry Reding,
On Fri, Sep 14, 2012 at 08:53:32AM -0700, Simon Glass wrote:
Hi,
On Wed, Sep 12, 2012 at 4:42 PM, Marek Vasut marex@denx.de wrote:
Dear Stephen Warren,
On 09/12/2012 04:38 PM, Marek Vasut wrote:
Dear 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.
Yes I agree, and I think it is pretty close - certainly much better than it used to be. The good thing about them being annoying is that they will likely get fixed :-)
I think I traced this to the copying of CSD a while back. The problem is that the transferred buffer is 8 bytes, so there's no way to make it aligned properly. Unfortunately the entailing discussion did not yield a solution at the time.
And how exactly does the MMC bounce buffer not help here?
Thierry
Best regards, Marek Vasut