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From: dianders@chromium.org (Doug Anderson)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2] ARM: exynos: add debug_ll_io_init() call in exynos_init_io()
Date: Wed,  5 Jun 2013 13:56:33 -0700	[thread overview]
Message-ID: <1370465793-7997-1-git-send-email-dianders@chromium.org> (raw)
In-Reply-To: <1370397539-21653-1-git-send-email-dianders@chromium.org>

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@chromium.org>
---
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

  parent reply	other threads:[~2013-06-05 20:56 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-06-05  1:58 [PATCH] ARM: samsung: avoid racy early printk at bootup Doug Anderson
2013-06-05  3:15 ` Olof Johansson
2013-06-05 20:56   ` Doug Anderson
2013-06-05 20:56 ` Doug Anderson [this message]
2013-06-05 21:12   ` [PATCH v2] ARM: exynos: add debug_ll_io_init() call in exynos_init_io() Olof Johansson
2013-06-05 23:32     ` Kukjin Kim
2013-06-08  1:12       ` Olof Johansson

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