diff options
| -rw-r--r-- | arch/powerpc/platforms/512x/clock-commonclk.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/arch/powerpc/platforms/512x/clock-commonclk.c b/arch/powerpc/platforms/512x/clock-commonclk.c index a97ce88cea6d..16569376b259 100644 --- a/arch/powerpc/platforms/512x/clock-commonclk.c +++ b/arch/powerpc/platforms/512x/clock-commonclk.c @@ -560,9 +560,21 @@ static void mpc512x_clk_setup_clock_tree(struct device_node *np, int busfreq) /* now setup anything below SYS and CSB and IPS */ clks[MPC512x_CLK_DDR_UG] = mpc512x_clk_factor("ddr-ug", "sys", 1, 2); - clks[MPC512x_CLK_SDHC_x4] = mpc512x_clk_factor("sdhc-x4", "csb", 4, 1); + + /* + * the Reference Manual discusses that for SDHC only even divide + * ratios are supported because clock domain synchronization + * between 'per' and 'ipg' is broken; + * keep the divider's bit 0 cleared (per reset value), and only + * allow to setup the divider's bits 7:1, which results in that + * only even divide ratios can get configured upon rate changes; + * keep the "x4" name because this bit shift hack is an internal + * implementation detail, the "fractional divider with quarters" + * semantics remains + */ + clks[MPC512x_CLK_SDHC_x4] = mpc512x_clk_factor("sdhc-x4", "csb", 2, 1); clks[MPC512x_CLK_SDHC_UG] = mpc512x_clk_divider("sdhc-ug", "sdhc-x4", 0, - &clkregs->scfr2, 0, 8, + &clkregs->scfr2, 1, 7, CLK_DIVIDER_ONE_BASED); clks[MPC512x_CLK_DIU_x4] = mpc512x_clk_factor("diu-x4", "csb", 4, 1); clks[MPC512x_CLK_DIU_UG] = mpc512x_clk_divider("diu-ug", "diu-x4", 0, |