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authorFelix Fietkau <nbd@openwrt.org>2015-09-11 16:32:45 +0000
committerFelix Fietkau <nbd@openwrt.org>2015-09-11 16:32:45 +0000
commitbc4f2c5ce4fa70444f5f59a23852fc81e4c092bb (patch)
tree166747c55981286ad33fd105d3962c5933f6c199 /target/linux/ar71xx
parentb7933a47bb8ef485fe503425a817780905372068 (diff)
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ar71xx: fix ar724x clock calculation
According to the AR7242 datasheet section 2.8, AR724X CPUs use a 40MHz input clock as the REF_CLK instead of 5MHz. The correct CPU PLL calculation procedure is as follows: CPU_PLL = (DIV * REF_CLK) / REF_DIV / 2. This patch is compatible with the current calculation procedure with default DIV and REF_DIV values. Test on both AR7240, AR7241 and AR7242. Signed-off-by: Weijie Gao <hackpascal@gmail.com> SVN-Revision: 46856
Diffstat (limited to 'target/linux/ar71xx')
-rw-r--r--target/linux/ar71xx/patches-4.1/634-MIPS-ath79-ar724x-clock-calculation-fixes.patch22
1 files changed, 22 insertions, 0 deletions
diff --git a/target/linux/ar71xx/patches-4.1/634-MIPS-ath79-ar724x-clock-calculation-fixes.patch b/target/linux/ar71xx/patches-4.1/634-MIPS-ath79-ar724x-clock-calculation-fixes.patch
new file mode 100644
index 0000000000..16d462137e
--- /dev/null
+++ b/target/linux/ar71xx/patches-4.1/634-MIPS-ath79-ar724x-clock-calculation-fixes.patch
@@ -0,0 +1,22 @@
+--- a/arch/mips/ath79/clock.c
++++ b/arch/mips/ath79/clock.c
+@@ -25,7 +25,7 @@
+ #include "common.h"
+
+ #define AR71XX_BASE_FREQ 40000000
+-#define AR724X_BASE_FREQ 5000000
++#define AR724X_BASE_FREQ 40000000
+ #define AR913X_BASE_FREQ 5000000
+
+ struct clk {
+@@ -99,8 +99,8 @@
+ div = ((pll >> AR724X_PLL_DIV_SHIFT) & AR724X_PLL_DIV_MASK);
+ freq = div * ref_rate;
+
+- div = ((pll >> AR724X_PLL_REF_DIV_SHIFT) & AR724X_PLL_REF_DIV_MASK);
+- freq *= div;
++ div = ((pll >> AR724X_PLL_REF_DIV_SHIFT) & AR724X_PLL_REF_DIV_MASK) * 2;
++ freq /= div;
+
+ cpu_rate = freq;
+