Re: [PATCH 1/3] ARM: dts: Add PMU reg node to exynos4210

From: Pankaj Dubey <pankaj.dubey@samsung.com>
To: Vikas Sajjan <sajjan.linux@gmail.com>
Cc: "linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	linux-kernel@vger.kernel.org,
	linux-samsung-soc <linux-samsung-soc@vger.kernel.org>,
	devicetree@vger.kernel.org, mark.rutland@arm.com,
	Kukjin Kim <kgene.kim@samsung.com>,
	linux@arm.linux.org.uk, pawel.moll@arm.com,
	ijc+devicetree@hellion.org.uk, Rob Herring <robh+dt@kernel.org>,
	galak@codeaurora.org, chow.kim@samsung.com,
	Tomasz Figa <t.figa@samsung.com>,
	Tomasz Figa <tomasz.figa@gmail.com>,
	sunil joshi <joshi@samsung.com>
Subject: Re: [PATCH 1/3] ARM: dts: Add PMU reg node to exynos4210
Date: Thu, 24 Apr 2014 21:57:33 +0900	[thread overview]
Message-ID: <53590A3D.1020308@samsung.com> (raw)
In-Reply-To: <CAGm_ybjfxprtLUX6Vs8QVvXoMOaHez4-Og8a9n3UevibvmzbZA@mail.gmail.com>

Hi Vikas,

On 04/24/2014 08:59 PM, Vikas Sajjan wrote:
> +Tomasz
>
>
> On Wed, Apr 2, 2014 at 1:32 PM, Pankaj Dubey <pankaj.dubey@samsung.com> wrote:
>> This patch adds pmu regnode to exynos4210 dtsi to handle
>> PMU register access via DT.
>>
>> Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com>
>> ---
>>   arch/arm/boot/dts/exynos4210.dtsi |    5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/exynos4210.dtsi b/arch/arm/boot/dts/exynos4210.dtsi
>> index cacf614..0a2c0fe 100644
>> --- a/arch/arm/boot/dts/exynos4210.dtsi
>> +++ b/arch/arm/boot/dts/exynos4210.dtsi
>> @@ -81,6 +81,11 @@
>>                  interrupts = <2 2>, <3 2>;
>>          };
>>
>> +       pmu_system_controller: system-controller@10020000 {
>> +               compatible = "samsung,exynos4210-pmu", "syscon";
>> +               reg = <0x10020000 0x5000>;
> Can we have 2 strings as "compatible" and these 2 strings are used by
> 2 different driver?
>
> Because once syscon driver gets probed, exynos-pmu.c [1] driver will
> never be probed.
>
> The new PMU driver [1] completely relies on this. With just
> exynos_defconfig, you will not notice this issue, since syscon is NOT
> enabled by exynos_defconfig. When I enabled "System Controller
> Register R/W Based on Regmap" in menuconfig, I could see PMU driver
> [1] is NEVER probed.
>
> Let me know, if I am missing something.
>
>   [1] http://www.spinics.net/lists/arm-kernel/msg319750.html

You are correct. We also missed this because "SYSCON" option was
not enabled in exynos_defconfig.
I noticed this during preparation of V2 when I planned to use
"early_syscon_init" [1] as suggested by Sylwester here [2].

In V2 I will take care of this. I hope soon I will be able to post second
version of this series, just waiting for testing and internal code review.

[1] https://lkml.org/lkml/2014/4/8/239
[2] https://lkml.org/lkml/2014/4/2/171
>
>
>> +       };
>> +
>>          pinctrl_0: pinctrl@11400000 {
>>                  compatible = "samsung,exynos4210-pinctrl";
>>                  reg = <0x11400000 0x1000>;
>> --
>> 1.7.10.4
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

-- 
Best Regards,
Pankaj Dubey