On Tue, Aug 27, 2019 at 11:54:31AM -0600, Stephen Warren wrote:
From: Stephen Warren swarren@nvidia.com
The current code in reserve_noncached() has two issues:
- The first update of gd->start_addr_sp always rounds down to a section
start. However, the equivalent calculation in cache.c:noncached_init() always first rounds up to a section start, then subtracts a section size. These two calculations differ if the initial value is already rounded to section alignment.
- The second update of gd->start_addr_sp subtracts exactly
CONFIG_SYS_NONCACHED_MEMORY, whereas the equivalent calculation in cache.c:noncached_init() rounds the noncached size up to section alignment before subtracting it. The two calculations differ if the noncached region size is not a multiple of the MMU section size.
In practice, one/both of those issues causes a practical problem on Jetson TX1; U-Boot triggers a synchronous abort during initialization, likely due to overlapping use of some memory region.
This change fixes both these issues by duplicating the exact calculations from noncached_init() into reserve_noncached().
However, this fix assumes that gd->start_addr_sp on entry to reserve_noncached() exactly matches mem_malloc_start on entry to noncached_init(). I haven't traced the code to see whether it absolutely guarantees this in all (or indeed any!) cases. Consequently, I added some comments in the hope that this condition will continue to be true.
Fixes: 5f7adb5b1c02 ("board_f: reserve noncached space below malloc area") Cc: Vikas Manocha vikas.manocha@st.com Signed-off-by: Stephen Warren swarren@nvidia.com
Applied to u-boot/master, thanks!