[U-Boot] [PATCH] board_f: fix noncached reservation calculation

Tom Rini trini at konsulko.com
Mon Sep 2 14:13:35 UTC 2019

On Tue, Aug 27, 2019 at 11:54:31AM -0600, Stephen Warren wrote:

> From: Stephen Warren <swarren at nvidia.com>
> The current code in reserve_noncached() has two issues:
> 1) 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.
> 2) 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 at st.com>
> Signed-off-by: Stephen Warren <swarren at nvidia.com>

Applied to u-boot/master, thanks!

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