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

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Message-ID: <3226068.I7g6oVyl1p@flatron>
Date:	Mon, 10 Jun 2013 20:53:09 +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 Monday 10 of June 2013 09:13:11 Tushar Behera wrote:
> On 06/08/2013 05:20 PM, Tomasz Figa wrote:
> > 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.
> 
> As of now, there are no other users of sclk_mpll other than a debug
> print within the same file.

OK.

> >>  	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.
> 
> But the older drivers (before migration to CCF) were using the clock
> "moutcore" (not "mout_core").

I mean, this should be placed in a separate patch, as this change is not 
"adding alias for cpufreq related clocks", but rather fixing a typo.

> >>  	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.
> 
> Same as above, "armclk" is used elsewhere, not "arm_clk".
> 
> >>  	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.
> I agree. Migration of exynos-cpufreq driver as a platform driver is the
> best solution. But unless someone picks up that work, cpufreq support
> for EXYNOS4 based systems is broken because of the incorrect clock
> aliases.

We have patches for this in our internal tree. I will clean them up a bit 
and submit soon.

Thanks,
Tomasz

> > This is especially important in case of regulators, which currently
> > have to be hacked by using vdd_arm as regulator name in device tree.
> Agree.
> 
> > CCing people that might be interested in this topic.
> > 
> > Best regards,
> > Tomasz
> 
> Thanks.
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