Re: [PATCH 08/14] OMAPDSS: DSS: add new clock calculation code

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On Friday 08 March 2013 05:22 PM, Tomi Valkeinen wrote:
Add new way to iterate over DSS clock divisors. dss_div_calc() provides
a generic way to go over all the divisors, within given clock range.
dss_div_calc() will call a callback function for each divider set,
making the function reusable for all use cases.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
---
  drivers/video/omap2/dss/dss.c |   36 ++++++++++++++++++++++++++++++++++++
  drivers/video/omap2/dss/dss.h |    3 +++
  2 files changed, 39 insertions(+)

diff --git a/drivers/video/omap2/dss/dss.c b/drivers/video/omap2/dss/dss.c
index 054c2a2..21a3dc8 100644
--- a/drivers/video/omap2/dss/dss.c
+++ b/drivers/video/omap2/dss/dss.c
@@ -473,6 +473,42 @@ int dss_calc_clock_rates(struct dss_clock_info *cinfo)
  	return 0;
  }

+bool dss_div_calc(unsigned long fck_min, dss_div_calc_func func, void *data)
+{
+	int fckd, fckd_start, fckd_stop;
+	unsigned long fck;
+	unsigned long fck_hw_max;
+	unsigned long fckd_hw_max;
+	unsigned long prate;
+
+	if (dss.dpll4_m4_ck == NULL) {
+		/* XXX can we change the clock on omap2? */

We can change dss_fclk1 on omap2, and the cclock2420_data.c and cclock2430_data.c have clksel structs which allow a set of dividers. The dividers are not continuous though, 1 to 12 and 16 are allowed. So we might need to change the code here a bit, if we want to change the clock in the first place.

Archit

+		fck = clk_get_rate(dss.dss_clk);
+		fckd = 1;
+
+		return func(fckd, fck, data);
+	}
+
+	fck_hw_max = dss_feat_get_param_max(FEAT_PARAM_DSS_FCK);
+	fckd_hw_max = dss.feat->fck_div_max;
+
+	prate = dss_get_dpll4_rate() * dss.feat->dss_fck_multiplier;
+
+	fck_min = fck_min ? fck_min : 1;
+
+	fckd_start = min(prate / fck_min, fckd_hw_max);
+	fckd_stop = max(DIV_ROUND_UP(prate, fck_hw_max), 1ul);
+
+	for (fckd = fckd_start; fckd >= fckd_stop; --fckd) {
+		fck = prate / fckd;
+
+		if (func(fckd, fck, data))
+			return true;
+	}
+
+	return false;
+}
+
  int dss_set_clock_div(struct dss_clock_info *cinfo)
  {
  	if (dss.dpll4_m4_ck) {
diff --git a/drivers/video/omap2/dss/dss.h b/drivers/video/omap2/dss/dss.h
index 0ff41dd..4180302 100644
--- a/drivers/video/omap2/dss/dss.h
+++ b/drivers/video/omap2/dss/dss.h
@@ -271,6 +271,9 @@ int dss_set_clock_div(struct dss_clock_info *cinfo);
  int dss_calc_clock_div(unsigned long req_pck, struct dss_clock_info *dss_cinfo,
  		struct dispc_clock_info *dispc_cinfo);

+typedef bool (*dss_div_calc_func)(int fckd, unsigned long fck, void *data);
+bool dss_div_calc(unsigned long fck_min, dss_div_calc_func func, void *data);
+
  /* SDI */
  int sdi_init_platform_driver(void) __init;
  void sdi_uninit_platform_driver(void) __exit;


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