clk: rockchip: change PLL setting for better clock jitter
dclk_vop0/1 is the source of HDMI TMDS clock in rk3288, usually we
use 594MHz for clock source of dclk_vop0/1.
HDMI CTS 7-9 require TMDS Clock jitter is lower than 0.25*Tbit:
TMDS clock(MHz) CTS require jitter (ps)
297 84.2
148.5 168
74.25 336
27 1247
PLL BW and VCO frequency effects the jitter of PLL output clock,
clock jitter is better if BW is lower or VCO frequency is higher.
If PLL use default setting of RK3066_PLL_RATE( 594000000, 2, 198, 4),
the TMDS Clock jitter is higher than 250ps, which means we can't
pass the test when TMDS clock is 297MHz or 148.5MHz.
If we use RK3066_PLL_RATE_BWADJ(594000000, 1, 198, 8, 1),
the TMDS Clock jitter is about 60ps and we can pass all test case.
So we need this patch to make hdmi si test pass.
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
2 files changed