omap2_dpll_round_rate() doesn't actually round the given rate, even if the name and the description so hints. Instead it only tries to find an exact rate match, or if that fails, return ~0 as an error.
What this basically means is that the user of the clock needs to know what rates the dpll can support, which obviously isn't right. This patch adds a simple method of rounding: during the iteration, the code keeps track of the closest rate match. If no exact match is found, the closest is returned. However, as it is unclear whether current drivers rely on the current behavior, the rounding functionality not enabled by default, but by setting DPLL_USE_ROUNDED_RATE for the DPLL. Signed-off-by: Tomi Valkeinen <[email protected]> --- arch/arm/mach-omap2/clkt_dpll.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/arch/arm/mach-omap2/clkt_dpll.c b/arch/arm/mach-omap2/clkt_dpll.c index 332af927f4d3..ddbb8d003719 100644 --- a/arch/arm/mach-omap2/clkt_dpll.c +++ b/arch/arm/mach-omap2/clkt_dpll.c @@ -298,6 +298,8 @@ long omap2_dpll_round_rate(struct clk_hw *hw, unsigned long target_rate, struct dpll_data *dd; unsigned long ref_rate; const char *clk_name; + unsigned long diff, closest_diff = ~0; + bool use_rounding = clk->flags & DPLL_USE_ROUNDED_RATE; if (!clk || !clk->dpll_data) return ~0; @@ -345,20 +347,31 @@ long omap2_dpll_round_rate(struct clk_hw *hw, unsigned long target_rate, pr_debug("clock: %s: m = %d: n = %d: new_rate = %lu\n", clk_name, m, n, new_rate); - if (target_rate == new_rate) { + diff = max(target_rate, new_rate) - min(target_rate, new_rate); + + if ((use_rounding && diff < closest_diff) || + (!use_rounding && diff == 0)) { + closest_diff = diff; + dd->last_rounded_m = m; dd->last_rounded_n = n; - dd->last_rounded_rate = target_rate; - break; + dd->last_rounded_rate = new_rate; + + if (diff == 0) + break; } } - if (target_rate != new_rate) { + if (closest_diff == ~0) { pr_debug("clock: %s: cannot round to rate %lu\n", clk_name, target_rate); return ~0; } - return target_rate; + if (closest_diff > 0) + pr_debug("clock: %s: rounded rate %lu to %lu\n", + clk_name, target_rate, dd->last_rounded_rate); + + return dd->last_rounded_rate; } -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
