[PATCH] i.MX25 GPT clock fix: ensure correct the clock source

[Mehnert, Torsten]

Request for comment and commit.


From: T. Mehnert <t.mehnert at eckelmann.de>
Date: Mon, 4 Jul 2011 15:53:30 +0200
Subject: [PATCH] i.MX25 GPT clock fix: ensure correct the clock source

This patch ensures, that Linux will take the correct clock source (AHB_DIV)
for gpt in the ARM i.MX25 implementation. The currect code depends on the reset
defaults of the CCM_MCR register. So on some boards it could happen that the
UPLL is used for clock source, which results in faulty time behavior in Linux.
In this case all delays or sleeps will will be faktor 1.8 too long.

Signed-off-by: Torsten Mehnert <t.mehnert at eckelmann.de>
---
 arch/arm/mach-imx/clock-imx25.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/arm/mach-imx/clock-imx25.c b/arch/arm/mach-imx/clock-imx25.c
index a65838f..bf1ecda 100644
--- a/arch/arm/mach-imx/clock-imx25.c
+++ b/arch/arm/mach-imx/clock-imx25.c
@@ -328,6 +328,10 @@ int __init mx25_clocks_init(void)
        __raw_writel(__raw_readl(CRM_BASE+0x64) | (1 << 7) | (1 << 0),
                        CRM_BASE + 0x64);

+       /* Clock source for gpt is ahb_div */
+       __raw_writel(__raw_readl(CRM_BASE+0x64) & ~(1 << 5),
+                       CRM_BASE + 0x64);
+
        mxc_timer_init(&gpt_clk, MX25_IO_ADDRESS(MX25_GPT1_BASE_ADDR), 54);

        return 0;
--
1.7.0.4

best regards,
        Torsten

Torsten Mehnert
Kälte- und Gebäudeleittechnik (KGL)

ECKELMANN AG
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D - 65205 Wiesbaden

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