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ARM: tegra: query_sdram_size() cleanup

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The return value of query_sdram_size() is assigned directly to
gd->ram_size in dram_init(). Adjust the return type to match the field
it's assigned to. This has the beneficial effect that on 64-bit systems,
the return value can correctly represent large RAM sizes over 4GB.

For similar reasons, change the type of variable size_bytes in the same
way.

query_sdram_size() would previously clip the detected RAM size to at most
just under 4GB in all cases, since on 32-bit systems, larger values could
not be represented. Disable this feature on 64-bit systems since the
representation restriction does not exist.

On 64-bit systems, never call get_ram_size() to validate the detected/
calculated RAM size. On any system with a secure OS/... carve-out, RAM
may not have a single contiguous usable area, and this can confuse
get_ram_size(). Ideally, we'd make this call conditional upon some other
flag that indicates specifically that a carve-out is actually in use. At
present, building for a 64-bit system is the best indication we have of
this fact. In fact, the call to get_ram_size() is not useful by the time
U-Boot runs on any system, since U-Boot (and potentially much other early
boot software) always runs from RAM on Tegra, so any mistakes in memory
controller register programming will already have manifested themselves
and prevented U-Boot from running to this point. In the future, we may
simply delete the call to get_ram_size() in all cases.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>
This commit is contained in:
Stephen Warren 2015-08-07 16:12:44 -06:00 committed by Tom Warren
parent a890316712
commit a5fc3d0b35
1 changed files with 10 additions and 4 deletions
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14
arch/arm/mach-tegra/board.c
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@ -66,10 +66,11 @@ bool tegra_cpu_is_non_secure(void)
#endif
/* Read the RAM size directly from the memory controller */
unsigned int query_sdram_size(void)
static phys_size_t query_sdram_size(void)
{
struct mc_ctlr *const mc = (struct mc_ctlr *)NV_PA_MC_BASE;
u32 emem_cfg, size_bytes;
u32 emem_cfg;
phys_size_t size_bytes;
emem_cfg = readl(&mc->mc_emem_cfg);
#if defined(CONFIG_TEGRA20)
@ -77,6 +78,7 @@ unsigned int query_sdram_size(void)
size_bytes = get_ram_size((void *)PHYS_SDRAM_1, emem_cfg * 1024);
#else
debug("mc->mc_emem_cfg (MEM_SIZE_MB) = 0x%08x\n", emem_cfg);
#ifndef CONFIG_PHYS_64BIT
/*
* If >=4GB RAM is present, the byte RAM size won't fit into 32-bits
* and will wrap. Clip the reported size to the maximum that a 32-bit
@ -84,9 +86,12 @@ unsigned int query_sdram_size(void)
*/
if (emem_cfg >= 4096) {
size_bytes = U32_MAX & ~(0x1000 - 1);
} else {
} else
#endif
{
/* RAM size EMC is programmed to. */
size_bytes = emem_cfg * 1024 * 1024;
size_bytes = (phys_size_t)emem_cfg * 1024 * 1024;
#ifndef CONFIG_ARM64
/*
* If all RAM fits within 32-bits, it can be accessed without
* LPAE, so go test the RAM size. Otherwise, we can't access
@ -97,6 +102,7 @@ unsigned int query_sdram_size(void)
if (emem_cfg <= (0 - PHYS_SDRAM_1) / (1024 * 1024))
size_bytes = get_ram_size((void *)PHYS_SDRAM_1,
size_bytes);
#endif
}
#endif