3.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Gabor Juhos <juhosg@xxxxxxxxxxx> 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 <juhosg@xxxxxxxxxxx> Cc: linux-mips@xxxxxxxxxxxxxx Patchwork: https://patchwork.linux-mips.org/patch/4305/ Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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);
