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| author | Douglas Anderson <dianders@chromium.org> | 2015-07-21 13:41:23 -0700 |
|---|---|---|
| committer | Stephen Boyd <sboyd@codeaurora.org> | 2015-07-28 11:59:12 -0700 |
| commit | 2bbfe00147a7c075f5c43e657ec218afea662819 (patch) | |
| tree | 25400d1f396ff92dc53a9153db5af4ebd31cffff /drivers/clk/rockchip/clk.h | |
| parent | 9cfad9bc472a4bdd5ee7d9e713113a9f5a676704 (diff) | |
| download | lwn-2bbfe00147a7c075f5c43e657ec218afea662819.tar.gz lwn-2bbfe00147a7c075f5c43e657ec218afea662819.zip | |
clk: rockchip: Fix PLL bandwidth
In the TRM we see that BWADJ is "a 12-bit bus that selects the values
1-4096 for the bandwidth divider (NB)":
NB = BWADJ[11:0] + 1
The recommended setting of NB: NB = NF / 2.
So:
NB = NF / 2
BWADJ[11:0] + 1 = NF / 2
BWADJ[11:0] = NF / 2 - 1
Right now, we have:
{ \
.rate = _rate##U, \
.nr = _nr, \
.nf = _nf, \
.no = _no, \
.bwadj = (_nf >> 1), \
}
That means we set bwadj to NF / 2, not NF / 2 - 1
All of this is a bit confusing because we specify "NR" (the 1-based
value), "NF" (the 1-based value), "NO" (the 1-based value), but
"BWADJ" (the 0-based value) instead of "NB" (the 1-based value).
Let's change to working with "NB" and fix the off by one error. This
may affect PLL jitter in a small way (hopefully for the better).
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Diffstat (limited to 'drivers/clk/rockchip/clk.h')
| -rw-r--r-- | drivers/clk/rockchip/clk.h | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/clk/rockchip/clk.h b/drivers/clk/rockchip/clk.h index 93ea335f2653..dc8ecb2673b7 100644 --- a/drivers/clk/rockchip/clk.h +++ b/drivers/clk/rockchip/clk.h @@ -83,16 +83,16 @@ enum rockchip_pll_type { .nr = _nr, \ .nf = _nf, \ .no = _no, \ - .bwadj = ((_nf) >> 1), \ + .nb = ((_nf) < 2) ? 1 : (_nf) >> 1, \ } -#define RK3066_PLL_RATE_BWADJ(_rate, _nr, _nf, _no, _bw) \ +#define RK3066_PLL_RATE_NB(_rate, _nr, _nf, _no, _nb) \ { \ .rate = _rate##U, \ .nr = _nr, \ .nf = _nf, \ .no = _no, \ - .bwadj = _bw, \ + .nb = _nb, \ } struct rockchip_pll_rate_table { @@ -100,7 +100,7 @@ struct rockchip_pll_rate_table { unsigned int nr; unsigned int nf; unsigned int no; - unsigned int bwadj; + unsigned int nb; }; /** |