Re: [PATCH 24/27] clk: rk3568: drop CLK_SET_RATE_PARENT from dclk_vop*

["Heiko Stübner" <heiko@sntech.de>]

Am Mittwoch, 26. Januar 2022, 15:55:46 CET schrieb Sascha Hauer:
> The pixel clocks dclk_vop[012] can be clocked from hpll, vpll, gpll or
> cpll. gpll and cpll also drive many other clocks, so changing the
> dclk_vop[012] clocks could change these other clocks as well. Drop
> CLK_SET_RATE_PARENT to fix that. With this change the VOP2 driver can
> only adjust the pixel clocks with the divider between the PLL and the
> dclk_vop[012] which means the user may have to adjust the PLL clock to a
> suitable rate using the assigned-clock-rate device tree property.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> ---
>  drivers/clk/rockchip/clk-rk3568.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clk/rockchip/clk-rk3568.c b/drivers/clk/rockchip/clk-rk3568.c
> index 9d889fc46811..7687c62d1fa8 100644
> --- a/drivers/clk/rockchip/clk-rk3568.c
> +++ b/drivers/clk/rockchip/clk-rk3568.c
> @@ -1044,13 +1044,13 @@ static struct rockchip_clk_branch rk3568_clk_branches[] __initdata = {
>  			RK3568_CLKGATE_CON(20), 8, GFLAGS),
>  	GATE(HCLK_VOP, "hclk_vop", "hclk_vo", 0,
>  			RK3568_CLKGATE_CON(20), 9, GFLAGS),
> -	COMPOSITE(DCLK_VOP0, "dclk_vop0", hpll_vpll_gpll_cpll_p, CLK_SET_RATE_PARENT | CLK_SET_RATE_NO_REPARENT,
> +	COMPOSITE(DCLK_VOP0, "dclk_vop0", hpll_vpll_gpll_cpll_p, CLK_SET_RATE_NO_REPARENT,

hmm, I'm wondering about the use of having CLK_SET_RATE_NO_REPARENT here
(and even adding it below).

Using SET_RATE_PARENT in the following patch for the hdmi-pll, should give
us at least a suitable rate for the hdmi output, so the vop using that
should already find a nice rate to use.

The normal system-PLLs don't normally don't change their rate at runtime,
so I think we should liberate the dclks to select a PLL that best matches
their target rate - so drop the CLK_SET_RATE_NO_REPARENT as well.

That way the DCLKs can change to another PLL source if that provides
a rate nearer to their target.

Heiko

>  			RK3568_CLKSEL_CON(39), 10, 2, MFLAGS, 0, 8, DFLAGS,
>  			RK3568_CLKGATE_CON(20), 10, GFLAGS),
> -	COMPOSITE(DCLK_VOP1, "dclk_vop1", hpll_vpll_gpll_cpll_p, CLK_SET_RATE_PARENT | CLK_SET_RATE_NO_REPARENT,
> +	COMPOSITE(DCLK_VOP1, "dclk_vop1", hpll_vpll_gpll_cpll_p, CLK_SET_RATE_NO_REPARENT,
>  			RK3568_CLKSEL_CON(40), 10, 2, MFLAGS, 0, 8, DFLAGS,
>  			RK3568_CLKGATE_CON(20), 11, GFLAGS),
> -	COMPOSITE(DCLK_VOP2, "dclk_vop2", hpll_vpll_gpll_cpll_p, 0,
> +	COMPOSITE(DCLK_VOP2, "dclk_vop2", hpll_vpll_gpll_cpll_p, CLK_SET_RATE_NO_REPARENT,
>  			RK3568_CLKSEL_CON(41), 10, 2, MFLAGS, 0, 8, DFLAGS,
>  			RK3568_CLKGATE_CON(20), 12, GFLAGS),
>  	GATE(CLK_VOP_PWM, "clk_vop_pwm", "xin24m", 0,
>