diff options
| author | Tomi Valkeinen <tomi.valkeinen@ti.com> | 2016-05-18 12:04:47 +0300 |
|---|---|---|
| committer | Tomi Valkeinen <tomi.valkeinen@ti.com> | 2016-05-19 20:19:09 +0300 |
| commit | f44b717c3d6908ac6590a1193a07c920d05e5a1d (patch) | |
| tree | 24dd7a259c0bfc4d70a8aee05e7f1189681d6276 | |
| parent | c107751d12cf40a5288d47edda53b2c4de2ff21c (diff) | |
| download | linux-f44b717c3d6908ac6590a1193a07c920d05e5a1d.tar.bz2 | |
drm/omap: add comments for PLL calculations
Add comments showing how the PLL clock rates are calculated.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
| -rw-r--r-- | drivers/gpu/drm/omapdrm/dss/pll.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/gpu/drm/omapdrm/dss/pll.c b/drivers/gpu/drm/omapdrm/dss/pll.c index 6daf7bc3a67a..4768a85e6c73 100644 --- a/drivers/gpu/drm/omapdrm/dss/pll.c +++ b/drivers/gpu/drm/omapdrm/dss/pll.c @@ -207,6 +207,10 @@ bool dss_pll_hsdiv_calc_a(const struct dss_pll *pll, unsigned long clkdco, return false; } +/* + * clkdco = clkin / n * m * 2 + * clkoutX = clkdco / mX + */ bool dss_pll_calc_a(const struct dss_pll *pll, unsigned long clkin, unsigned long pll_min, unsigned long pll_max, dss_pll_calc_func func, void *data) @@ -252,6 +256,9 @@ bool dss_pll_calc_a(const struct dss_pll *pll, unsigned long clkin, * This calculates a PLL config that will provide the target_clkout rate * for clkout. Additionally clkdco rate will be the same as clkout rate * when clkout rate is >= min_clkdco. + * + * clkdco = clkin / n * m + clkin / n * mf / 262144 + * clkout = clkdco / m2 */ bool dss_pll_calc_b(const struct dss_pll *pll, unsigned long clkin, unsigned long target_clkout, struct dss_pll_clock_info *cinfo) |