linux-kernel - Re: [PATCH 1/2] clk: samsung: Don't build ARMv8 clock drivers on ARMv7

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Date:	Tue, 17 Nov 2015 15:01:18 +0100
From:	Sylwester Nawrocki <s.nawrocki@...sung.com>
To:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
Cc:	"pankaj.dubey" <pankaj.dubey@...sung.com>,
	Tomasz Figa <tomasz.figa@...il.com>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	linux-samsung-soc@...r.kernel.org, linux-clk@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Kukjin Kim <kgene@...nel.org>, Olof Johansson <olof@...om.net>,
	Arnd Bergmann <arnd@...db.de>,
	linux-arm-kernel@...ts.infradead.org,
	Kevin Hilman <khilman@...aro.org>
Subject: Re: [PATCH 1/2] clk: samsung: Don't build ARMv8 clock drivers on ARMv7

On 17/11/15 05:39, Krzysztof Kozlowski wrote:
> On 17.11.2015 13:31, pankaj.dubey wrote:
>> On Monday 16 November 2015 07:06 AM, Krzysztof Kozlowski wrote:
>>> Currently the Exynos5433 (ARMv8 SoC) clock driver depends on ARCH_EXYNOS
>>> so it is built also on ARMv7. This does not bring any kind of benefit.
>>> There won't be a single kernel image for ARMv7 and ARMv8 SoCs (like
>>> multi_v7 for ARMv7).
>>>
>>> Instead build clock drivers only for respective SoC's architecture.
>>>
>>> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
>>> ---
>>>  drivers/clk/samsung/Kconfig  | 13 +++++++++++++
>>>  drivers/clk/samsung/Makefile |  4 ++--
>>>  2 files changed, 15 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/clk/samsung/Kconfig b/drivers/clk/samsung/Kconfig
>>> index 84196ecdaa12..5f138fc4d84d 100644
>>> --- a/drivers/clk/samsung/Kconfig
>>> +++ b/drivers/clk/samsung/Kconfig
>>> @@ -2,6 +2,7 @@ config COMMON_CLK_SAMSUNG
>>>  	bool
>>>  	select COMMON_CLK
>>>  
>>> +# ARMv7 SoCs:
>>>  config S3C2410_COMMON_CLK
>>>  	bool
>>>  	select COMMON_CLK_SAMSUNG
>>> @@ -24,3 +25,15 @@ config S3C2443_COMMON_CLK
>>>  	bool
>>>  	select COMMON_CLK_SAMSUNG
>>>  
>>> +# ARMv8 SoCs:
>>> +config EXYNOS5433_COMMON_CLK
>>> +	bool
>>> +	depends on ARM64 || COMPILE_TEST
>>> +	default ARCH_EXYNOS
>>> +	select COMMON_CLK_SAMSUNG
>>> +
>>> +config EXYNOS7_COMMON_CLK
>>> +	bool
>>> +	depends on ARM64 || COMPILE_TEST
>>> +	default ARCH_EXYNOS
>>> +	select COMMON_CLK_SAMSUNG
>>> diff --git a/drivers/clk/samsung/Makefile b/drivers/clk/samsung/Makefile
>>> index 5f6833ea355d..a31332a24ef4 100644
>>> --- a/drivers/clk/samsung/Makefile
>>> +++ b/drivers/clk/samsung/Makefile
>>> @@ -10,11 +10,11 @@ obj-$(CONFIG_SOC_EXYNOS5250)	+= clk-exynos5250.o
>>>  obj-$(CONFIG_SOC_EXYNOS5260)	+= clk-exynos5260.o
>>>  obj-$(CONFIG_SOC_EXYNOS5410)	+= clk-exynos5410.o
>>>  obj-$(CONFIG_SOC_EXYNOS5420)	+= clk-exynos5420.o
>>> -obj-$(CONFIG_ARCH_EXYNOS)	+= clk-exynos5433.o
>>> +obj-$(CONFIG_EXYNOS5433_COMMON_CLK)	+= clk-exynos5433.o
>>>  obj-$(CONFIG_SOC_EXYNOS5440)	+= clk-exynos5440.o
>>>  obj-$(CONFIG_ARCH_EXYNOS)	+= clk-exynos-audss.o
>>>  obj-$(CONFIG_ARCH_EXYNOS)	+= clk-exynos-clkout.o
>>> -obj-$(CONFIG_ARCH_EXYNOS7)	+= clk-exynos7.o
>>> +obj-$(CONFIG_EXYNOS7_COMMON_CLK)	+= clk-exynos7.o
>>>  obj-$(CONFIG_S3C2410_COMMON_CLK)+= clk-s3c2410.o
>>>  obj-$(CONFIG_S3C2410_COMMON_DCLK)+= clk-s3c2410-dclk.o
>>>  obj-$(CONFIG_S3C2412_COMMON_CLK)+= clk-s3c2412.o
>>>
>>
>> So in this approach we need to add separate config for clock support of
>> each ARM64 Exynos64 SoC. Is this fine?
>>
>> Can we club compilation of each ARM64 Exynos SoC clock file under
>> EXYNOS7_COMMON_CLK? As for all ARM64 SoC there is single defconfig and
>> binary.
> 
> Yes, it can be one config symbol for all clocks of ARMv8 Exynos SoCs.
> From my point of view both has some advantages and disadvantages (kernel
> size, granularity, number of Kconfig symbols etc.) and I don't mind
> choosing different than I selected before.
> 
> Any opinion from Samsung clock maintainers? Which do you prefer?

It would have been a bit unfortunate to not be able to exclude
the unneeded clk drivers from build.  From my side both patches
look like a step in right direction.

For the $subject patch:

Acked-by: Sylwester Nawrocki <s.nawrocki@...sung.com>

-- 
Thanks
Sylwester
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