linux-kernel - Re: [PATCH 1/2] clk: exynos4: Add PCLK

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Message-ID: <CABxcv=myq4VeMamstjVR2cpWCiD_FM91ncYYVKd4jRF=nB5zZQ@mail.gmail.com>
Date:	Thu, 11 Jun 2015 14:58:33 +0200
From:	Javier Martinez Canillas <javier@...hile0.org>
To:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
Cc:	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	Mike Turquette <mturquette@...aro.org>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Tomasz Figa <tomasz.figa@...il.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Kukjin Kim <kgene@...nel.org>,
	Sylwester Nawrocki <s.nawrocki@...sung.com>,
	linux-clk@...r.kernel.org,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [PATCH 1/2] clk: exynos4: Add PCLK_ADC gate clock on Exynos4x12

Hello Krzysztof,

On Thu, Jun 11, 2015 at 2:40 PM, Krzysztof Kozlowski
<k.kozlowski@...sung.com> wrote:
> W dniu 11.06.2015 o 21:15, Javier Martinez Canillas pisze:
>> Hello Krzysztof,
>>
>> On Thu, Jun 11, 2015 at 12:43 PM, Krzysztof Kozlowski
>> <k.kozlowski@...sung.com> wrote:
>>> W dniu 11.06.2015 o 17:26, Krzysztof Kozlowski pisze:
>>>> Add proper gate clock for the Analog to Digital Converter (ADC) on
>>>> Exynos4x12.
>>>>
>>>> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
>>>> ---
>>>>  drivers/clk/samsung/clk-exynos4.c   | 3 +++
>>>>  include/dt-bindings/clock/exynos4.h | 5 ++++-
>>>>  2 files changed, 7 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/clk/samsung/clk-exynos4.c b/drivers/clk/samsung/clk-exynos4.c
>>>> index 714d6ba782c8..5f32410a01f8 100644
>>>> --- a/drivers/clk/samsung/clk-exynos4.c
>>>> +++ b/drivers/clk/samsung/clk-exynos4.c
>>>> @@ -85,6 +85,7 @@
>>>>  #define DIV_PERIL4           0xc560
>>>>  #define DIV_PERIL5           0xc564
>>>>  #define E4X12_DIV_CAM1               0xc568
>>>> +#define E4X12_GATE_BUS_FSYS1 0xc744
>>>>  #define GATE_SCLK_CAM                0xc820
>>>>  #define GATE_IP_CAM          0xc920
>>>>  #define GATE_IP_TV           0xc924
>>>> @@ -1095,6 +1096,8 @@ static struct samsung_gate_clock exynos4x12_gate_clks[] __initdata = {
>>>>               0),
>>>>       GATE(CLK_PPMUIMAGE, "ppmuimage", "aclk200", E4X12_GATE_IP_IMAGE, 9, 0,
>>>>               0),
>>>> +     GATE(CLK_PCLK_ADC, "pclk_adc", "aclk133", E4X12_GATE_BUS_FSYS1, 16, 0,
>>>> +             0),
>>>
>>> Now I have even simpler idea. Don't add new clock id but just define
>>> here the CLK_TSADC as:
>>> GATE(CLK_TSADC, "tsadc", "aclk133", E4X12_GATE_BUS_FSYS1, 16, 0, 0);
>>>
>>> With this change the second patch wouldn't be needed however this does
>>> not reflect the Exynos 4x12 datasheet.
>>>
>>> Any comments?
>>>
>>
>> I think it's better to reflect the datasheet so I prefer your original
>> patch.
>
> Yeah, I also like sticking to datasheet but maybe it is not always worth
> to reproduce the datasheet in 100%. It is just thinking out loud.
>

Agreed.

>> Also, wouldn't changing the CLK_TSADC gate definition cause a
>> regression on an Exynos4210 board that is using the tsadc clock? or
>> maybe I misunderstood the explanation of your Patch 2/2?
>
> No, no. The Exynos4210 would be unchanged. It has the CLK_TSADC - both
> in hardware and in kernel driver. The Exynos4x12 SoCs don't have so we can:
> 1. Add new CLK_PCLK_ADC (id and clock) reflecting datasheet.
> 2. Add only CLK_TSADC clock  on Exynos4x12 which will be using the
> register of PCLK_ADC. The id would stay the same as on Exynos4210.
>

I see, thanks for the explanation. Both approaches seems sensible for
me then, I don't have a strong opinion on either though.

> Best regards,
> Krzysztof
>

Best regards,
Javier
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