This is a note to let you know that I've just added the patch titled
MIPS: ath79: use correct fractional dividers for {CPU,DDR}_PLL on AR934x
to the 3.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mips-ath79-use-correct-fractional-dividers-for-cpu-ddr-_pll-on-ar934x.patch
and it can be found in the queue-3.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 65fc7f9957c52ad4fdf4ee5dfe3a75aa0a633d39 Mon Sep 17 00:00:00 2001
From: Gabor Juhos <[email protected]>
Date: Sat, 1 Sep 2012 18:46:00 +0200
Subject: MIPS: ath79: use correct fractional dividers for {CPU,DDR}_PLL on
AR934x
From: Gabor Juhos <[email protected]>
commit 65fc7f9957c52ad4fdf4ee5dfe3a75aa0a633d39 upstream.
The current dividers in the code are wrong and this
leads to broken CPU frequency calculation on boards
where the fractional part is used.
For example, if the SoC is running from a 40MHz
reference clock, refdiv=1, nint=14, outdiv=0 and
nfrac=31 the real frequency is 579.375MHz but the
current code calculates 569.687MHz instead.
Because the system time is indirectly related to
the CPU frequency the broken computation causes
drift in the system time.
The correct divider is 2^6 for the CPU PLL and 2^10
for the DDR PLL. Use the correct values to fix the
issue.
Signed-off-by: Gabor Juhos <[email protected]>
Cc: [email protected]
Patchwork: https://patchwork.linux-mips.org/patch/4305/
Signed-off-by: Ralf Baechle <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/mips/ath79/clock.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/mips/ath79/clock.c
+++ b/arch/mips/ath79/clock.c
@@ -189,7 +189,7 @@ static void __init ar934x_clocks_init(vo
AR934X_PLL_CPU_CONFIG_NFRAC_MASK;
cpu_pll = nint * ath79_ref_clk.rate / ref_div;
- cpu_pll += frac * ath79_ref_clk.rate / (ref_div * (2 << 6));
+ cpu_pll += frac * ath79_ref_clk.rate / (ref_div * (1 << 6));
cpu_pll /= (1 << out_div);
pll = ath79_pll_rr(AR934X_PLL_DDR_CONFIG_REG);
@@ -203,7 +203,7 @@ static void __init ar934x_clocks_init(vo
AR934X_PLL_DDR_CONFIG_NFRAC_MASK;
ddr_pll = nint * ath79_ref_clk.rate / ref_div;
- ddr_pll += frac * ath79_ref_clk.rate / (ref_div * (2 << 10));
+ ddr_pll += frac * ath79_ref_clk.rate / (ref_div * (1 << 10));
ddr_pll /= (1 << out_div);
clk_ctrl = ath79_pll_rr(AR934X_PLL_CPU_DDR_CLK_CTRL_REG);
Patches currently in stable-queue which might be from [email protected] are
queue-3.6/mips-ath79-use-correct-fractional-dividers-for-cpu-ddr-_pll-on-ar934x.patch
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