| Message ID | 20180118184532.6856-4-jbrunet@baylibre.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On 01/19/18 02:45, Jerome Brunet wrote: > The pll driver perform the rate calculation in Mhz, which adds an > unnecessary rounding down to the Mhz of the rate. Use 64bits long > integer to perform this calculation safely on meson8b and perform the > calculation in Hz instead > > Fixes: 7a29a869434e ("clk: meson: Add support for Meson clock controller") > Signed-off-by: Jerome Brunet <jbrunet@baylibre.com> > --- > drivers/clk/meson/clk-pll.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/drivers/clk/meson/clk-pll.c b/drivers/clk/meson/clk-pll.c > index 2614341fc4ad..fa4cec13d6e8 100644 > --- a/drivers/clk/meson/clk-pll.c > +++ b/drivers/clk/meson/clk-pll.c > @@ -51,8 +51,7 @@ static unsigned long meson_clk_pll_recalc_rate(struct clk_hw *hw, > { > struct meson_clk_pll *pll = to_meson_clk_pll(hw); > struct parm *p; > - unsigned long parent_rate_mhz = parent_rate / 1000000; > - unsigned long rate_mhz; > + u64 rate; > u16 n, m, frac = 0, od, od2 = 0; > u32 reg; > > @@ -74,17 +73,18 @@ static unsigned long meson_clk_pll_recalc_rate(struct clk_hw *hw, > od2 = PARM_GET(p->width, p->shift, reg); > } > > + rate = (u64)m * parent_rate; > + > p = &pll->frac; > if (p->width) { > reg = readl(pll->base + p->reg_off); > frac = PARM_GET(p->width, p->shift, reg); > - rate_mhz = (parent_rate_mhz * m + \ > - (parent_rate_mhz * frac >> 12)) * 2 / n; > - rate_mhz = rate_mhz >> od >> od2; > - } else > - rate_mhz = (parent_rate_mhz * m / n) >> od >> od2; > > - return rate_mhz * 1000000; > + rate += (u64)parent_rate * frac >> 12; > + rate *= 2; > + } > + > + return (rate / n) >> od >> od2; > } > > static long meson_clk_pll_round_rate(struct clk_hw *hw, unsigned long rate, > Hi Jerome: This is exactly what I want to propose, thanks for pushing this! With the whole series, the fixed_pll is more accurate, and the ethernet driver on axg is capable of choosing fclk_div2.. Yixun
diff --git a/drivers/clk/meson/clk-pll.c b/drivers/clk/meson/clk-pll.c index 2614341fc4ad..fa4cec13d6e8 100644 --- a/drivers/clk/meson/clk-pll.c +++ b/drivers/clk/meson/clk-pll.c @@ -51,8 +51,7 @@ static unsigned long meson_clk_pll_recalc_rate(struct clk_hw *hw, { struct meson_clk_pll *pll = to_meson_clk_pll(hw); struct parm *p; - unsigned long parent_rate_mhz = parent_rate / 1000000; - unsigned long rate_mhz; + u64 rate; u16 n, m, frac = 0, od, od2 = 0; u32 reg; @@ -74,17 +73,18 @@ static unsigned long meson_clk_pll_recalc_rate(struct clk_hw *hw, od2 = PARM_GET(p->width, p->shift, reg); } + rate = (u64)m * parent_rate; + p = &pll->frac; if (p->width) { reg = readl(pll->base + p->reg_off); frac = PARM_GET(p->width, p->shift, reg); - rate_mhz = (parent_rate_mhz * m + \ - (parent_rate_mhz * frac >> 12)) * 2 / n; - rate_mhz = rate_mhz >> od >> od2; - } else - rate_mhz = (parent_rate_mhz * m / n) >> od >> od2; - return rate_mhz * 1000000; + rate += (u64)parent_rate * frac >> 12; + rate *= 2; + } + + return (rate / n) >> od >> od2; } static long meson_clk_pll_round_rate(struct clk_hw *hw, unsigned long rate,
The pll driver perform the rate calculation in Mhz, which adds an unnecessary rounding down to the Mhz of the rate. Use 64bits long integer to perform this calculation safely on meson8b and perform the calculation in Hz instead Fixes: 7a29a869434e ("clk: meson: Add support for Meson clock controller") Signed-off-by: Jerome Brunet <jbrunet@baylibre.com> --- drivers/clk/meson/clk-pll.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)