linux-kernel - Re: [PATCH 2/2] clk: exynos4: Add alias for cpufreq related clocks

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Date:	Sat, 08 Jun 2013 13:50:52 +0200
From:	Tomasz Figa <tomasz.figa@...il.com>
To:	Tushar Behera <tushar.behera@...aro.org>
Cc:	linux-kernel@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
	mturquette@...aro.org, kgene.kim@...sung.com, patches@...aro.org,
	swarren@...dotorg.org, grant.likely@...aro.org,
	rob.herring@...xeda.com, devicetree-discuss@...ts.ozlabs.org,
	broonie@...nel.org, l.majewski@...sung.com, s.nawrocki@...sung.com
Subject: Re: [PATCH 2/2] clk: exynos4: Add alias for cpufreq related clocks

On Thursday 06 of June 2013 16:52:28 Tushar Behera wrote:
> cpufreq driver for EXYNOS4 based SoCs are not platform drivers, hence
> we cannot currently pass the clock names through a device tree node.
> Instead, we need to make them available through a global alias.
> 
> 'armclk', 'moutcore', 'mout_mpll' and 'mout_apll' clock aliases are
> defined.
> 
> Signed-off-by: Tushar Behera <tushar.behera@...aro.org>
> ---
>  drivers/clk/samsung/clk-exynos4.c |   10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/clk/samsung/clk-exynos4.c
> b/drivers/clk/samsung/clk-exynos4.c index 3c1f888..1e4258a 100644
> --- a/drivers/clk/samsung/clk-exynos4.c
> +++ b/drivers/clk/samsung/clk-exynos4.c
> @@ -356,8 +356,8 @@ struct samsung_fixed_rate_clock
> exynos4210_fixed_rate_clks[] __initdata = {
> 
>  /* list of mux clocks supported in all exynos4 soc's */
>  struct samsung_mux_clock exynos4_mux_clks[] __initdata = {
> -	MUX_F(mout_apll, "mout_apll", mout_apll_p, SRC_CPU, 0, 1,
> -			CLK_SET_RATE_PARENT, 0),
> +	MUX_FA(mout_apll, "mout_apll", mout_apll_p, SRC_CPU, 0, 1,
> +			CLK_SET_RATE_PARENT, 0, "mout_apll"),
>  	MUX(none, "mout_hdmi", mout_hdmi_p, SRC_TV, 0, 1),
>  	MUX(none, "mout_mfc1", sclk_evpll_p, SRC_MFC, 4, 1),
>  	MUX(none, "mout_mfc", mout_mfc_p, SRC_MFC, 8, 1),
> @@ -385,9 +385,9 @@ struct samsung_mux_clock exynos4210_mux_clks[]
> __initdata = { MUX(none, "mout_g2d", mout_g2d_p, E4210_SRC_IMAGE, 8,
> 1),
>  	MUX(none, "mout_fimd1", group1_p4210, E4210_SRC_LCD1, 0, 4),
>  	MUX(none, "mout_mipi1", group1_p4210, E4210_SRC_LCD1, 12, 4),
> -	MUX_A(sclk_mpll, "sclk_mpll", mout_mpll_p, SRC_CPU, 8, 1, 
"sclk_mpll"),
> +	MUX_A(sclk_mpll, "sclk_mpll", mout_mpll_p, SRC_CPU, 8, 1, 
"mout_mpll"),

This is not fully compliant with patch description. I'm not sure if there 
weren't any users of the sclk_mpll alias.

>  	MUX_A(mout_core, "mout_core", mout_core_p4210,
> -			SRC_CPU, 16, 1, "mout_core"),
> +			SRC_CPU, 16, 1, "moutcore"),

IMHO those typo corrections are not part of this patch.

>  	MUX_A(sclk_vpll, "sclk_vpll", sclk_vpll_p4210,
>  			SRC_TOP0, 8, 1, "sclk_vpll"),
>  	MUX(mout_fimc0, "mout_fimc0", group1_p4210, SRC_CAM, 0, 4),
> @@ -534,7 +534,7 @@ struct samsung_div_clock exynos4_div_clks[]
> __initdata = { DIV(none, "div_spi_pre2", "div_spi2", DIV_PERIL2, 8, 8),
>  	DIV(none, "div_audio1", "mout_audio1", DIV_PERIL4, 0, 4),
>  	DIV(none, "div_audio2", "mout_audio2", DIV_PERIL4, 16, 4),
> -	DIV_A(arm_clk, "arm_clk", "div_core2", DIV_CPU0, 28, 3, 
"arm_clk"),
> +	DIV_A(arm_clk, "arm_clk", "div_core2", DIV_CPU0, 28, 3, "armclk"),

Same here.

>  	DIV_A(sclk_apll, "sclk_apll", "mout_apll",
>  			DIV_CPU0, 24, 3, "sclk_apll"),
>  	DIV_F(none, "div_mipi_pre0", "div_mipi0", DIV_LCD0, 20, 4,

Basically I don't like the idea of those global aliases, which IMHO should 
be completely dropped. Someone might not like it, but I'd go with the 
conversion of our cpufreq drivers to platform drivers instead, which could 
receive things like clocks and regulators using DT-based lookups.

This is especially important in case of regulators, which currently have 
to be hacked by using vdd_arm as regulator name in device tree.

CCing people that might be interested in this topic.

Best regards,
Tomasz

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