If the early MMU mapping of the UART happens to get booted out of the
TLB between the start of paging_init() and when we finally re-add the
UART at the very end of s3c_init_cpu(), we'll get a hang at bootup if
we've got early_printk enabled. Avoid this hang by calling
debug_ll_io_init() early.
Without this patch, you can reliably reproduce a hang when early
printk is enabled by adding flush_tlb_all() at the start of
exynos_init_io(). After this patch the hang goes away.
Signed-off-by: Doug Anderson <dianders@xxxxxxxxxxxx>
---
Changes in v2:
- Use debug_ll_io_init() instead of reordering printks and adding
warnings. Thanks Olof!
arch/arm/mach-exynos/common.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/arm/mach-exynos/common.c b/arch/arm/mach-exynos/common.c
index 027c9e7..f7e504b 100644
--- a/arch/arm/mach-exynos/common.c
+++ b/arch/arm/mach-exynos/common.c
@@ -386,6 +386,8 @@ int __init exynos_fdt_map_chipid(unsigned long node, const char *uname,
void __init exynos_init_io(struct map_desc *mach_desc, int size)
{
+ debug_ll_io_init();
+
#ifdef CONFIG_OF
if (initial_boot_params)
of_scan_flat_dt(exynos_fdt_map_chipid, NULL);
--
1.8.3
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