linux-kernel - Re: [PATCH v1 13/50] clk: samsung: add DPLL rate table in Exynos5420

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Date:   Tue, 16 Jul 2019 18:31:03 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Lukasz Luba <l.luba@...tner.samsung.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-clk@...r.kernel.org
Cc:     mturquette@...libre.com, sboyd@...nel.org,
        b.zolnierkie@...sung.com, krzk@...nel.org, kgene@...nel.org,
        mark.rutland@....com, robh+dt@...nel.org,
        kyungmin.park@...sung.com, a.hajda@...sung.com,
        m.szyprowski@...sung.com, s.nawrocki@...sung.com,
        myungjoo.ham@...sung.com
Subject: Re: [PATCH v1 13/50] clk: samsung: add DPLL rate table in
 Exynos5420

Hi,

Also, you better to merge patch13/patch15/patch16 to one patch
in order to add the PLL table for DPLL/MPLL/SPLL.

And I have a question. Are there any use-case to change
the PLL frequency for DPLL/MPLL/SPLL?

On 19. 7. 15. 오후 9:43, Lukasz Luba wrote:
> The DPLL has fixed frequency left by the bootloader and it is not possible
> to change it. With this patch the DPLL gets rate table the same for the
> whole  PLL family (similar as APLL, KPLL according to RM) so the frequency
> might be changed to one of the values defined there.
> It is needed for further patches which change the DPLL frequency to feed
> the clocks with proper base.
> It also sets CLK_IS_CRITICAL for SCLK_DPLL due to some drivers which could
> disable master clock, which is then populated higher and tries to disable
> PLL, which casues system crash. The flag is needed for this kind of use
> cases.
> 
> Signed-off-by: Lukasz Luba <l.luba@...tner.samsung.com>
> ---
>  drivers/clk/samsung/clk-exynos5420.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/samsung/clk-exynos5420.c b/drivers/clk/samsung/clk-exynos5420.c
> index 7f8221527633..2395b02ce8c5 100644
> --- a/drivers/clk/samsung/clk-exynos5420.c
> +++ b/drivers/clk/samsung/clk-exynos5420.c
> @@ -694,7 +694,8 @@ static const struct samsung_mux_clock exynos5x_mux_clks[] __initconst = {
>  	MUX(0, "mout_sclk_rpll", mout_rpll_p, SRC_TOP6, 16, 1),
>  	MUX_F(CLK_MOUT_EPLL, "mout_sclk_epll", mout_epll_p, SRC_TOP6, 20, 1,
>  			CLK_SET_RATE_PARENT, 0),
> -	MUX(0, "mout_sclk_dpll", mout_dpll_p, SRC_TOP6, 24, 1),
> +	MUX_F(CLK_MOUT_SCLK_DPLL, "mout_sclk_dpll", mout_dpll_p,
> +			SRC_TOP6, 24, 1, CLK_IS_CRITICAL, 0),
>  	MUX(0, "mout_sclk_cpll", mout_cpll_p, SRC_TOP6, 28, 1),
>  
>  	MUX(CLK_MOUT_SW_ACLK400_ISP, "mout_sw_aclk400_isp",
> @@ -1514,6 +1515,7 @@ static void __init exynos5x_clk_init(struct device_node *np,
>  
>  	if (_get_rate("fin_pll") == 24 * MHZ) {
>  		exynos5x_plls[apll].rate_table = exynos5420_pll2550x_24mhz_tbl;
> +		exynos5x_plls[dpll].rate_table = exynos5420_pll2550x_24mhz_tbl;
>  		exynos5x_plls[epll].rate_table = exynos5420_epll_24mhz_tbl;
>  		exynos5x_plls[kpll].rate_table = exynos5420_pll2550x_24mhz_tbl;
>  	}
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics