19 Oct
2015
19 Oct
'15
7:52 a.m.
Hello Thomas,
On Mon, 12 Oct 2015 20:55:03 +0800, Thomas Chou thomas@wytron.com.tw wrote:
Hi Marek,
On 10/12/2015 06:32 PM, Marek Vasut wrote:
Wouldn't invalidate_dcache_range() be enough here ? You don't care about the data in the newly allocated area at this point I guess -- either you fill them in and then flush, for DMA from CPU to device OR you receive data from device to CPU and then you invalidate this buffer again.
No. We cannot use invalidate cache here. This is related to cache design of nios2, kind of direct mapped cache.
Not sure I'm getting this, so for my own education: what prevents from invalidating the cache, or IOW, what would happen if it was invalidated at this point rather than flushed?
Best regards, Thomas
Amicalement,
--
Albert.