On ap4evb PLLC2 is used as a parent clock for the HDMI clock. To configure the
HDMI clock with the highest precision this patch scans all available PLLC2
frequencies and picks up the best one.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
---
arch/arm/mach-shmobile/board-ap4evb.c | 60 +++++++++++++++++++++++++++++++++
1 files changed, 60 insertions(+), 0 deletions(-)
diff --git a/arch/arm/mach-shmobile/board-ap4evb.c b/arch/arm/mach-shmobile/board-ap4evb.c
index 7d0a8c4..8676e26 100644
--- a/arch/arm/mach-shmobile/board-ap4evb.c
+++ b/arch/arm/mach-shmobile/board-ap4evb.c
@@ -637,9 +637,69 @@ static struct platform_device lcdc1_device = {
},
};
+#define MAX_DIVISOR 63
+
+static long ap4evb_clk_optimize(unsigned long target, unsigned long *best_freq,
+ unsigned long *parent_freq)
+{
+ struct cpufreq_frequency_table *freq, *best = NULL;
+ unsigned long error = ULONG_MAX, freq_high, freq_low, div;
+
+ for (freq = pllc2_clk.freq_table; freq->frequency != CPUFREQ_TABLE_END;
+ freq++) {
+ if (freq->frequency < target) {
+ if (error > target - freq->frequency) {
+ error = target - freq->frequency;
+ best = freq;
+ if (best_freq)
+ *best_freq = freq->frequency;
+ }
+ continue;
+ }
+ div = freq->frequency / target;
+ if (div > MAX_DIVISOR)
+ div = MAX_DIVISOR;
+ freq_high = freq->frequency / div;
+ freq_low = freq->frequency / (div + 1);
+ if (freq_high - target < error) {
+ error = freq_high - target;
+ best = freq;
+ if (best_freq)
+ *best_freq = freq_high;
+ }
+ if (target - freq_low < error) {
+ error = target - freq_low;
+ best = freq;
+ if (best_freq)
+ *best_freq = freq_low;
+ }
+ pr_debug("%u / %lu = %lu, / %lu = %lu, best %lu, parent %u\n",
+ freq->frequency, div, freq_high, div + 1, freq_low,
+ *best_freq, best->frequency);
+ if (!error)
+ break;
+ }
+ if (parent_freq)
+ *parent_freq = best->frequency;
+ return error;
+}
+
+static int ap4evb_clk_set_rate(struct clk *clk, unsigned long rate)
+{
+ return clk_set_rate(clk->parent, rate);
+}
+
+static unsigned long ap4evb_clk_get_rate(struct clk *clk)
+{
+ return clk_get_rate(clk->parent);
+}
+
static struct sh_mobile_hdmi_info hdmi_info = {
.lcd_chan = &sh_mobile_lcdc1_info.ch[0],
.lcd_dev = &lcdc1_device.dev,
+ .clk_optimize_parent = ap4evb_clk_optimize,
+ .clk_set_rate_parent = ap4evb_clk_set_rate,
+ .clk_get_rate_parent = ap4evb_clk_get_rate,
};
static struct resource hdmi_resources[] = {
--
1.7.1
--
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